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Ochronosis is rarely considered a cause for knee synovitis due to its rare occurrence. It starts affecting the joint from the third decade onward causing premature joint damage. The damaged joint and surrounding tissue present as blackish decolorated mass and can surprise the operating surgeon, unless diagnosed beforehand. Prior diagnosis helps both the anesthetist and operating surgeon to better handle the associated complications of ochronosis during surgery. Diagnosis is essentially based on prior knowledge of the disease and its markers. Here, we report a rare case of ochronosis of the knee that was treated elsewhere previously as tuberculosis of the knee. A history evaluation along with intraoperative findings helped arrive at the possible diagnosis of ochronosis. Total synovectomy was done. Postoperative improvement of visual analog scale score was significant and the patient was satisfied with the pain relief attained through treatment. Early diagnosis and timely management is critical to avoid unwanted complication related to both anesthesia and surgery pertaining to the disease. Knowledge of skin markers and urine darkening helps in identifying the disease early.

Muconic acid (MA) is a dicarboxylic acid used for the production of industrially relevant chemicals such as adipic acid, terephthalic acid, and caprolactam. Because the synthesis of these polymer precursors generates toxic intermediates by utilizing petroleum-derived chemicals and corrosive catalysts, the development of alternative strategies for the bio-based production of MA has garnered significant interest. Plants produce organic carbon skeletons by harvesting carbon dioxide and energy from the sun, and therefore represent advantageous hosts for engineered metabolic pathways towards the manufacturing of chemicals. In this work, we engineered Arabidopsis to demonstrate that plants can serve as green factories for the bio-manufacturing of MA. In particular, dual expression of plastid-targeted bacterial salicylate hydroxylase (NahG) and catechol 1,2-dioxygenase (CatA) resulted in the conversion of the endogenous salicylic acid (SA) pool into MA via catechol. Sequential increase of SA derived from the shikimate pathway was achieved by expressing plastid-targeted versions of bacterial salicylate synthase (Irp9) and feedback-resistant 3-deoxy-D-arabino-heptulosonate synthase (AroG). Introducing this SA over-producing strategy into engineered plants that co-express NahG and CatA resulted in a 50-fold increase in MA titers. Considering that MA was easily recovered from senesced plant biomass after harvest, we envision the phytoproduction of MA as a beneficial option to add value to bioenergy crops.

Background: Halogenated aromatic compounds are more resistant to microbial degradation than non-halogenated aromatic compounds. Microbial degradation of sodium benzoate in the presence of sodium 3-chlorobenzoate is of interest. The ability to degrade aromatic compounds is largely determined by the substrate specificity of the first enzyme that initiates degradation, namely, benzoate 1,2-dioxygenase for benzoate degradation, and 3-chlorobenzoate 1,2-dioxygenase for 3-chlorobenzoate degradation. In this study, the perspective of immobilized cells of Rhodococcus opacus 1CP actinobacterium for degradation of benzoate and 3-chlorobenzoate was explored. Methods: The biosensor approach (a membrane microbial sensor based on immobilized cells of Rhodococcus opacus 1CP and the Clark-type oxygen electrode as a transducer) was applied to evaluate the actinobacterial cells’ responses to benzoate and 3-chlorobenzoate in the absence of both enzymes, benzoate 1,2-dioxygenase and 3-chlorobenzoate 1,2-dioxygenase, or in the presence of one of the said enzymes. Results: Data obtained show that 1CP actinobacterium possessed a constitutive system for the transport of benzoate and 3-chlorobenzoate into culture cells. The affinity of the transport system for benzoate was higher than that for 3-chlorobenzoate. Moreover, adaptation to one substrate did not preclude the use of the second substrate. Probably, porins facilitated the penetration of benzoate and 3-chlorobenzoate into 1CP cells. Analyzing V vs. S dependencies, negative cooperativity was found, when benzoate 1,2-dioxygenase bound substrate (3-chlorobenzoate), while positive cooperativity was determined at benzoate binding. The observed difference could be associated with the presence of at least two systems of 3-chlorobenzoate transport into actinobacterial cells and allosteric interaction of active sites of benzoate 1,2-dioxygenase in the presence of 3-chlorobenzoate. Conclusions: The membrane microbial sensor based on immobilized Rhodococcus opacus 1CP cells could be useful as a perspective tool for comparative evaluation of enzymes of complex structure such as benzoate- and 3-chlorobenzoate 1,2-dioxygenase.

ABSTRACT Monoaromatics, such as benzene, toluene, ethylbenzene and xylene (BTEX), are simple aromatic compound that are highly toxic due to their high solubility nature. Many chemical and physical methods for their degradation and breakup into nontoxic products are available, but still use of microorganism is preferred over these processes. In this present study Bacillus pumilus MVSV3 (Accession number JN089707), a less explored bacteria in the field of BTEX degradation, isolated from petroleum contaminated soil is utilized for BTEX degradation. At optimized conditions the isolate degraded 150 mg/L of BTEX completely within 48 h. GC-MS analysis revealed that the microorganism produces catechol and muconic acid during degradation indicating an ortho pathway of degradation. Enzyme assays were carried out to identify and characterize catechol 1, 2- dioxygenase (C12D). The optimal temperature and pH for the enzyme activity was identified as 35 (C and 7.5, respectively. SDS-PAGE revealed the molecular weight of the enzyme to be approximately 35,000 Da. Zymography analysis indicated the presence of three isoforms of the enzyme. Hence Bacillus pumilus MVSV3 and the isolated C12D, proved to be efficient in degrading the toxic aromatic compounds.

Catechol 1,2-dioxygenase is the key enzyme that catalyzes the cleavage of the aromatic ring of catechol. We explored the genetic diversity of catechol 1,2-dioxygenase in the fecal microbial metagenome by PCR with degenerate primers. A total of 35 gene fragments of C12O were retrieved from microbial DNA in the feces of pygmy loris. Based on phylogenetic analysis, most sequences were closely related to C12O sequences from Acinetobacter. A full-length C12O gene was directly cloned, heterologously expressed in Escherichia coli, and biochemically characterized. Purified catPL12 had optimum pH and temperature pH 8.0 and 25 °C and retained 31 and 50% of its maximum activity when assayed at 0 and 35 °C, respectively. The enzyme was stable at 25 and 37 °C, retaining 100% activity after pre-incubation for 1 h. The kinetic parameters of catPL12 were determined. The enzyme had apparent Km of 67 µM, Vmax of 7.3 U/mg, and kcat of 4.2 s−1 for catechol, and the cleavage activities for 3-methylcatechol, 4-methylcatechol, and 4-chlorocatechol were much less than for catechol, and no activity with hydroquinone or protocatechuate was detected. This study is the first to report the molecular and biochemical characterizations of a cold-adapted catechol 1,2-dioxygenase from a fecal microbial metagenome. [ABSTRACT FROM AUTHOR]

Benzoate 1,2-dioxygenase (BDO) of Rhodococcus opacus 1CP, which carried out the initial attack on benzoate, was earlier shown to be the enzyme with a narrow substrate specificity. A kinetics of interaction between benzoate 1,2-dioxygenase and substituted benzoates was assessed taking into account the enlarged list of the type of inhibition and using whole cells grown on benzoate. The type of inhibition was determined and the constants of a reaction of BDO with benzoate in the presence of 2-chlorobenzoate (2CBA), 3,5-dichlorobenzoate (3,5DCBA), and 3-methylbenzoate (3MBA) were calculated. For 2CBA and 3MBA, the types of inhibition were classified as biparametrically disсoordinated inhibition and transient inhibition (from activation towards inhibition), respectively. The process of not widely recognized pseudoinhibition of a BDO reaction with benzoate by 3,5DCBA was assessed by the vector method for the representation of enzymatic reactions. Ki value was determined for 2CBA, 3MBA, and 3,5DCBA as 337.5, 870.3, and 14.7 μM, respectively. [ABSTRACT FROM AUTHOR]

The alpha-Proteobacterium Pseudaminobacter salicylatoxidans BN12 forms a peculiar gentisate 1,2-dioxygenase (SDO) that xidatively cleaves gentisate (2,5-dihydroxybenzoate) and additionally 1-hydroxy-2-naphthoate, salicylate and various amino-, chloro-, fluoro-, hydroxy- and methylsalicylates. In the present study, the conversion of 5-fluorosalicylate by this enzyme was analysed using various analytical techniques. Spectrophotometric assays showed that the conversion of 5-fluorosalicylate by the purified enzyme resulted in the formation of a new unstable intermediate showing an absorbance maximum at λmax = 292 nm. The analysis of the enzymatic reaction by HPLC showed that two main products with absorbance maxima at λmax= 292-296 nm were formed from 5-fluorosalicylate. The same two products (although in different relative proportions) were also formed when the SDO transformed 5-chlorosalicylate or when a purified 5-nitrosalicylate 1,2-dioxygenase from Bradyrhizobium sp. JS329 oxidized 5-nitrosalicylate. A whole cell system with recombinant Escherichia coli cells overexpressing the SDO activity was established in order to produce larger amounts of the reaction products. The reaction products were subsequently identified by 1H-NMR and mass spectrometry as stereoisomers of 2-oxo-3-(5-oxofuran-2-ylidine)propanoic acid. The release of fluoride in the course of the dioxygenolytic cleavage reaction was confirmed by ion-chromatography and 19F-NMR. [ABSTRACT FROM AUTHOR]

Two genes coding proteins with phenol hydroxylase and catechol 1,2-dioxygenase enzyme activities which take part in the degradation pathway of phenolic compounds in Antarctic fungal strain A. fumigatus AL 3 have been identified. The primers applied in the PCR analyses for both genes were designed on the basis of the identical genes sequences of A. fumigatus strain Af293. For the detection of phenol hydroxylase and catechol 1,2-dioxygenase genes were created and used two sets each consisted of 3 pairs of primers. The obtained oligonucleotide DNA fragments were sequenced by Sanger method. The overlapped three fragments for each one of the investigated genes were combined. The sequence obtained for phenol hydroxylase gene (1398 bp without introns) was organized into 3 exons and 2 introns. The length of the partial catechol 1,2-dioxygenase gene count without introns was 642 bp. It included 4 exons and 3 introns. The basic logical alignment search confirmed that the phenol hydroxylase gene had 99% nucleotide identity with the corresponding gene of A. fumigatus Af293. The same percent of identity of the catechol 1,2-dioxygenase genes of A. fumigatus Af293 and A. fumigatus AL 3 was established. The translation of the obtained DNA sequences revealed a protein with phenol hydroxylase activity consisting of 465 amino acids as well as a protein with catechol 1,2-dioxigenase activity consisting of 213 amino acids. The proximity of the studied proteins with closely related enzymes with similar functions were demonstrated on the created distant tree's cladograms. [ABSTRACT FROM AUTHOR]

The chrysene-degrading bacterium Pseudoxanthomonas sp. PNK-04 was isolated from a coal sample. Three novel metabolites, hydroxyphenanthroic acid, 1-hydroxy-2-naphthoic acid and salicylic acid, were identified by TLC, HPLC and MS. Key enzyme activities, namely 1-hydroxy-2-naphthoate hydroxylase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase and catechol-1,2-dioxygenase, were noted in the cell-free extract. These results suggest that chrysene is catabolized via hydroxyphenanthroic acid, 1-hydroxy-2-naphthoic acid, salicylic acid and catechol. The terminal aromatic metabolite, catechol, is then catabolized by catechol-1,2-dioxygenase to cis,cis-muconic acid, ultimately forming TCA cycle intermediates. Based on these studies, the proposed catabolic pathway for chrysene degradation by strain PNK-04 is chrysene → hydroxyphenanthroic acid → 1-hydroxy-2-naphthoic acid → 1,2-dihydroxynaphthalene → salicylic acid → catechol → cis,cis-muconic acid. [ABSTRACT FROM AUTHOR]

Stenotrophomonas sp. RMSK capable of degrading acenaphthylene as a sole source of carbon and energy was isolated from coal sample. Metabolites produced were analyzed and characterized by TLC, HPLC and mass spectrometry. Identification of naphthalene-1,8-dicarboxylic acid, 1-naphthoic acid, 1,2-dihydroxynaphthalene, salicylate and detection of key enzymes namely 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase and catechol- 1,2-dioxygenase in the cell free extract suggest that acenaphthylene metabolized via 1,2-dihydroxynaphthalene, salicylate and catechol. The terminal metabolite, catechol was then metabolized by catechol- 1,2-dioxygenase to cis,cis-muconic acid, ultimately forming TCA cycle intermediates. Based on these studies, the proposed metabolic pathway in strain RMSK is, acenaphthylene→ naphthalene-1,8- dicarboxylic acid→ 1-naphthoic acid→ 1,2-dihydroxynaphthalene→ salicylic acid→ catechol→ cis,cis-muconic acid. [ABSTRACT FROM AUTHOR]

The strains Rhodococcus sp. 400, R. rhodochrous 172, and R. opacus 6a utilize 4-methylbenzoate as the only carbon and energy source. 4-Methylcatechol is a key intermediate of biodegradation. Its further conversion by all the strains proceeds via ortho-cleavage. The specific activity of catechol 1,2-dioxygenase assayed in crude extracts of Rhodococcus sp. 400 and R. rhodochrous 172 with 3- and 4-methylcatechols does not exceed the enzyme activity assayed with catechol. Two catechol 1,2-dioxygenases have been purified from the biomass of R. opacus strain 6a grown with 4-methylbenzoate. These enzymes differed in molecular mass and physicochemical and catalytic properties. One of these enzymes belongs to the type of enzymes cleaving the catechol ring and known as methylcatechol 1,2-dioxygenases. In bacteria of the Rhodococcus genus, such an enzyme is described here for the first time. [ABSTRACT FROM AUTHOR]

A bphC gene (915 bp) encoding 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC) was amplified by PCR from Dyella ginsengisoli LA-4, which was heterologously expressed in Escherichia coli. The purified His-Tag BphC was able to catalyze the meta-cleavage reaction of the dihydroxylated aromatic rings. According to the specificity constant ( Kcat/ Km) of BphC_LA-4, the specificity of BphC_LA-4 was determined in the following order: 2,3-dihydroxybiphenyl>3-methylcatechol>catechol>4-chlorocatechol>4-methylcatechol. The experimental data were consistent with the prediction of enzyme–substrate complexes. The highest specific activity of BphC_LA-4 was 118.3 U mg−1 for 2,3-dihydroxybiphenyl. [ABSTRACT FROM AUTHOR]

A soil bacterium isolated from a contaminated site degraded phenol when provided as the sole carbon and energy source in the medium. The bacterium was identified as Xanthobacter flavus MTCC 9130. This microbial strain was able to tolerate phenol up to 1000 mg L-1 concentration. The lag phase increased with the increase in phenol concentration. The optimum growth temperature was 37°C. The organism efficiently utilized phenol and could degrade it completely within 120 h when initial concentration was less than 600 mg L-1. Degradation of phenol was through ortho pathway, enzyme assay through cell-free extract exhibited the presence of catechol 1,2-dioxygenase. The specific activity was 0.146 μ mol min-1 mg-1 protein. However, higher concentrations of phenol in the medium had a negative effect on the growth of the bacterium. Hence this ability of Xanthobacter flavus can be effectively used for bioremediation studies of phenol-contaminated sites. [ABSTRACT FROM AUTHOR]

Aims: Catechol 1,2-dioxygenase is a key enzyme in the degradation of monoaromatic pollutants. The detection of this gene is in focus today but recently designed degenerate primers are not always suitable. Rhodococcus species are important members of the bacterial community involved in the degradation of aromatic contaminants and their specific detection could help assess functions and activities in the contaminated environments. To reach this aim, specific PCR primer sets were designed for the detection of Rhodococcus related catechol 1,2-dioxygenase genes. Methods and Results: Primers were tested with genetically well-characterized strains isolated in this study and community DNA samples were used as template for Rhodococcus specific PCR as well. The sequences of the catabolic gene in question were subjected to multiple alignment and a phylogenetic tree was created and compared to a 16S rRNA gene based Rhodococcus tree. A strong coherence was observed between the phylogenetic trees. Conclusions: The results strongly support the opinion that there was no recent lateral gene transfer among Rhodococcus species in the case of catechol 1,2-dioxygenase. Significance and Impact of the Study: In gasoline contaminated environments, aromatic hydrocarbon degrading Rhodococcus populations can be identified based upon the detection and sequence analysis of catechol 1,2-dioxygenase gene. [ABSTRACT FROM AUTHOR]

The article focuses on the scientific concept of the tphA1n and tphA2nA3n genes of Comamonas sp. E6 perhaps code for the terephthalate. To characterize E6 TPADO, these genes were expressed in a His-tagged form in Escherichia coli, and the recombinant proteins were purified. TPADO activity was reconstituted from TphAln and TphA2nA3n, indicating that TPADO consists of a reductase and a terminal oxy- genase component. .

Focussing on the role of chlorocatechol 1,2-dioxygenase (CC12O), an oxygen-dependent key enzyme in the aerobic catabolism of chlorobenzene (CB), Pseudomonas veronii strain UFZ B549, Acidovorax facilis strain UFZ B530, and a community of indigenous groundwater bacteria were amended with CB degradation under either oxic or hypoxic conditions. All cultures readily degraded CB at high oxygen availability, but had differing abilities to completely degrade CB when exposed to oxygen limitation. For the three cultures very distinct oxygen half-saturation constants (0.3-11.7 μM) for the respective CC12Os were obtained and protein analysis showed that high affinity-type A. facilis and low affinity-type P. veronii express CC12Os, which belong to different structural clusters. From this a functional relation between CC12O type and the ability to cope with efficient ring fission under oxygen limitation is anticipated. Extremely high oxygen affinities for CC12Os support the assumption that truly oxic environments are not an essential requirement to degrade chloro(aromatic) compounds. Tiny quantities of oxygen permanently resupplied will sufficiently maintain the growth of microaerophilic specialists with the ability to transform chloro(aromatics) via catechol intermediates. [ABSTRACT FROM AUTHOR]

Abstract: The crystallographic structure of salicylate 1,2-dioxygenase (SDO), a new ring fission dioxygenase from the naphthalenesulfonate-degrading strain Pseudaminobacter salicylatoxidans BN12, which oxidizes salicylate to 2-oxohepta-3,5-dienedioic acid by a novel ring fission mechanism, has been solved by molecular replacement techniques and refined at 2.9 Å resolution (R free 26.1%; R-factor 19.3%). SDO is a homo-tetramer member of type III extradiol-type dioxygenases with a subunit topology characteristic of the bicupin β-barrel folds. The catalytic center contains a mononuclear iron(II) ion coordinated to three histidine residues (His119, His121, and His160), located within the N-terminal domain in a solvent-accessible pocket. SDO is markedly different from the known gentisate 1,2-dioxygenases (GDO) or 1-hydroxy-2-naphthoate dioxygenase because of its unique ability to oxidatively cleave numerous salicylates, gentisates and 1-hydroxy-2-naphthoate with high catalytic efficiency. The comparison of the structure and substrate specificity for a series of different substrates with the corresponding data for several GDOs and the docking of salicylates/gentisates in the active site of SDO, allowed the identification of several active site residues responsible for differences of substrate specificity. In particular, a more defined electron density of the N-terminal region allowed the discovery of a novel structure fragment in SDO previously unobserved in GDO. This region contributes several residues to the active site that influence substrate specificity for both of these enzymes. Implications on the catalytic mechanism are discussed. [Copyright &y& Elsevier]

A 1,125-bp long ORF encoding a novel gentisate 1,2-dioxygenase with two-domain bicupins was cloned from Silicibacter pomeroyi DSS-3 and expressed in Escherichia coli. The resulting product was purified to homogeneity and partially characterized. Non-reductive SDS-PAGE and gel filtration showed that the active recombinant gentisate 1,2-dioxygenase had an estimated molecular mass of 132 kDa, and reductive SDS-PAGE indicated an approximate size of 45 kDa. The enzyme thus appears to be a homotrimeric protein. This is in contrast to the homotetrameric or dimeric protein of the gentisate 1,2-dioxygenases that have been characterized thus far. The K m and K cat/ K m for gentisate were 12 μM and 653 × 104 M−1 s−1; the pI was 4.6–4.8. It was optimally active at 40°C and pH 8.0. [ABSTRACT FROM AUTHOR]

Abstract: This work describes a new genetic organization and co-regulation of a cluster of genes involved in the first steps of phenol and benzene catabolic pathways in Pseudomonas sp. M1, different from the established models for Pseudomonas upper pathway. Pseudomonas sp. M1 was isolated by others from the sediments of the Rhine River and exhibits an exceptional biodegradation ability towards a wide range of toxic and/or recalcitrant compounds. Although the taxonomic classification of strain M1 could not be determined, we found in a previous study that Pseudomonas citronellolis is the closest species. The genetic organization characterized in this study, the phc (phenol catabolism) genes, includes eight clustered genes, encoding a catechol 1,2-dioxygenase (phcA), a multicomponent phenol hydroxylase (phcKLMNOP) and the transcriptional regulator PhcR (phcR). PhcR controls the transcription of the referred seven clustered genes from two catabolic promoters: Pa (for phcA) and Pk (for phcKLMNOP). In agreement with in silico prediction, the activity of Pa and Pk promoters was proved to depend on the presence of σ54. Both promoters are phenol and benzene inducible and evidence supporting the unique σ54-dependent co-regulation of the phenol/benzene inducible genes phcA and phcKLMNOP, mediated by PhcR, was obtained. [Copyright &y& Elsevier]

Abstract: Pseudomonas alcaligenes NCIMB 9867 (strain P25X) is known to synthesize two isofunctional gentisate 1,2-dioxygenases (GDO; EC 1.13.11.4) as well as other enzymes involved in the degradation of xylenols and cresols via the gentisate pathway. The hbzE gene encoding what is possibly the strictly inducible gentisate 1,2-dioxygenase II (GDO-II) was cloned, overexpressed and purified as a hexahistidine fusion protein from Escherichia coli. Active recombinant GDO-II had an estimated molecular mass of 150kDa and is likely a tetrameric protein with a subunit mass of ∼40kDa, similar to the previously characterized gentisate 1,2-dioxygenase I (GDO-I) encoded by xlnE. However, GDO-II was unable to utilize gentisate that is substituted at the carbon-4 position, unlike GDO-I which had broader substrate specificity. GDO-II also possessed different kinetic characteristics when compared to GDO-I. The hbzE-encoded GDO-II shared higher sequence identities (53%) with GDOs from Ralstonia sp. U2 and Polaromonas naphthalenivorans CJ2, compared with only 35% identity with the xlnE-encoded GDO-I. The hbzE gene was found to be part of a cluster of nine genes including the putative regulatory gene designated hbzR, which encodes an LysR-type regulator and is divergently transcribed from the other genes of the hbzHIJKLFED cluster. [Copyright &y& Elsevier]

The gene encoding gentisate 1,2-dioxygenase from a soil-borne Gram-negative bacterium, Ralstonia solanacearum GMI 1000, was cloned and overexpressed in Escherichia coli. The resulting product incorporated a (His) 6 tag was purified to homogeneity from the harvested cell extracts by affinity chromatography. SDS-PAGE showed that the polypeptide exhibited an approximate molecular mass of 38 kDa. The optimal temperature and pH for gentisate cleavage catalysed by the enzyme were 30 °C and 8.0, respectively. The K m of the enzyme was determined to be 56 μM. The pI is 4.6–4.8. Moreover, site-directed mutagenesis revealed that His105, His 107, and His 146 are the crucial residues involved in the catalytic activity of gentisate 1,2-dioxygenase from Ralstonia solanacearum GMI 1000. [ABSTRACT FROM AUTHOR]

Abstract: A series of mononuclear iron(III) complexes with containing phenolate donor of substituted-salicylaldimine based ligands [Fe(L1)(TCC)]·CH3OH (1), [Fe(L2)(TCC)]·CH3OH (2), [Fe(L3)(TCC)] (3), and [Fe(L4)(TCC)] (4) have been prepared and studied as functional models for catechol dioxygenases (H2TCC=tetrachlorocatechol, or HL1 = N′-(salicylaldimine)-N,N-diethyldiethylenetriamine, HL2 = N′-(5-Br-salicylaldimine)-N,N-diethyldiethylenetriamine, HL3 = N′-(4,6-dimethoxy-salycyl-aldimine)-N,N-diethyl-diethylenetriamine, HL4 = N′-(4-methoxy-salicylaldimine)-N,N-diethyl-diethylenetriamine). They are structural models for inhibitors of enzyme-substrate adducts from the reactions of catechol 1,2-dioxygenases. Complexes 1–4 were characterized by spectroscopic methods and X-ray crystal structural analysis. The coordination sphere of Fe(III) atom of 1–4 is distorted octahedral with N3O3 donor set from the ligand and the substrate TCC occupying cis position, and Fe(III) is in high-spin (S =5/2) electronic ground state. The in situ prepared iron(III) complexes without TCC, [Fe(L1)Cl2], [Fe(L2)Cl2], [Fe(L3)Cl2], and [Fe(L4)Cl2] are reactive towards intradiol cleavage of the 3,5-di-tert-butylcatechol (H2DBC) in the presence of O2 or air. The reaction rate of catechol 1,2-dioxygenase depends on the redox potential and acidity of iron(III) ions in complexes as well as the substituent effect of the ligands. We have identified the reaction products and proposed the mechanism of the reactions of these iron(III) complexes with H2DBC with O2. [Copyright &y& Elsevier]

Structural and energetic properties of proteolytic fragments originated from naphthalene 1,2-dioxygenase (NDO) enzyme were investigated through a computational approach. A library of fragments was generated by using an algorithm able to identify specified regions of the primary sequence and simulating cleavages on target sites. Structure of the fragments was optimised by Monte Carlo and molecular dynamics (MD) methods and the conformational and energetic properties were compared with those of the native enzyme. Protonation states of ionizable groups were predicted on the basis of effective pKa values. Proteolytic fragments structurally similar to NDO were docked to naphthalene and interaction energies were evaluated by using MD computations. Many candidate fragments were able to maintain properties close to those which occur in the native conditions, while structures obtained by cleavages on the β-subunit of the NDO asymmetric unit were found to be rather unstable. Among the investigated structures, owing to comparable energetic and structural characteristics, 146-694 proteolytic fragment may be a promising alternative to NDO enzyme for complexation and biodegradation of naphthalenes. [ABSTRACT FROM AUTHOR]

A eukaryotic catechol 1,2-dioxygenase (1,2-CTD) was produced from a Candida albicans TL3 that possesses high tolerance for phenol and strong phenol degrading activity. The 1,2-CTD was purified via ammonium sulfate precipitation, Sephadex G-75 gel filtration, and HiTrap Q Sepharose column chromatography. The enzyme was purified to homogeneity and found to be a homodimer with a subunit molecular weight of 32,000. Each subunit contained one iron. The optimal temperature and pH were 25°C and 8.0, respectively. Substrate analysis showed that the purified enzyme was a type I catechol 1,2-dioxygenase. This is the first time that a 1,2-CTD from a eukaryote ( Candida albicans) has been characterized. Peptide sequencing on fragments of 1,2-CTD by Edman degradation and MALDI-TOF/TOF mass analyses provided information of amino acid sequences for BLAST analysis, the outcome of the BLAST revealed that this eukaryotic 1,2-CTD has high identity with a hypothetical protein, CaO19_12036, from Candida albicans SC5314. We conclude that the hypothetical protein is 1,2-CTD. [ABSTRACT FROM AUTHOR]

The article focuses on the encoding of a putative gentisate 1,2-dioxygenase in the dibenzothiophene degradation gene cluster from Xanthobacter polyaromaticivorans 127W. The amino acid sequence showed high similarity in sequence with dioxygenases from Pseudomonas alcaligenes, Bradyrhizobium japonicum and Pseudomonas aeruginosa.

Degradation of para-toluate by Rhodococcus opacus 1cp was investigated. Activities of the key enzymes of this process, catechol 1,2-dioxygenase and muconate cycloisomerase, are detected in this microorganism. Growth on p-toluate was accompanied by induction of two catechol 1,2-dioxygenases. The substrate specificity and physicochemical properties of one enzyme are identical to those of chlorocatechol 1,2-dioxygenase; induction of the latter enzyme was observed during R. opacus 1cp growth on 4-chlorophenol. The other enzyme isolated from the biomass grown on p-toluate exhibited lower rate of chlorinated substrate cleavage compared to the catechol substrate. However, this enzyme is not identical to the catechol 1,2-dioxygenase cloned in this strain within the benzoate catabolism operon. This supports the hypothesis on the existence of multiple forms of dioxygenases as adaptive reactions of microorganisms in response to environmental stress. [ABSTRACT FROM AUTHOR]

Abstract: Catechol 1,2-dioxygenase from Pseudomonas putida was isolated and immobilized in calcium alginate hydrogels. The gel matrix could effectively entrap the enzyme, with high retention of activity. Following immobilization, catechol 1,2-dioxygenase exhibited improved storage stability and activity in the presence of organic solvents, and performed better at higher incubation temperatures. In addition, the enzyme retained most of its catalytic efficiency after successive operational cycles. The hypothesis that enhancement of enzyme stability after immobilization is related to the stabilization of its multimeric structure has been investigated. Electron paramagnetic resonance (EPR) spectroscopy indicates that the environment of the non-heme iron center was not affected during the immobilization process and the ability for the substrate (catechol) binding at the metal center was retained. Catalytic constants for free and immobilized enzyme were practically equivalent. The influence of internal and external mass-transfer limitations on the initial reaction rates of dioxygenase-catalyzed oxidation reactions has been investigated. [Copyright &y& Elsevier]

Abstract: Pseudomonas aeruginosa TKU002, capable of growing significantly on acidic side pH 5.5 and benzoic acid as a sole carbon source, was isolated from enrichment culture accumulation of catechol. An intracellular catechol 1,2-dioxygenase (CD) produced by P. aeruginosa TKU002 was purified and characterized. The TKU002 CD was found to have unique characteristics different to other microbial CDs. The unique characteristics include the smallest molecular mass of 22kDa, the most acidic pI value of lower than 4, and the highest cleavage activity to the substrate, pyrogallol. Different to other CD producing strains, P. aeruginosa TKU002 produced CD at a lower pH of 5.5 when benzoate was used as the sole carbon source. The TKU002 CD was a monomer with a K m of 5.9μM. The TKU002 CD showed 36% and 14% sequence coverage rate with protocatechuate 3,4-dioxygenase β-subunit of P. aeruginosa UCBPP-COG3485 and catechol 1,2-dioxygenase of P. aeruginosa PA01, respectively, and possessed one matched peptide (YLWDDFAYATR). In conclusion, this is the first report of a microbial CD with the smallest molecular mass, the most acidic pI value, the highest specific activity to the substrate pyrogallol, and the most acidic medium for CD production. [Copyright &y& Elsevier]

Abstract: The detection of aromatic compounds from pesticides and industrial wastewater has become of great interest, since these compounds withstand chemical oxidation and biological degradation, accumulating in the environment. In this work, a highly sensitive biosensor for detecting catechol was obtained with the immobilization of Cl-catechol 1,2-dioxygenase (CCD) in nanostructured films. CCD layers were alternated with poly(amidoamine) generation 4 (PAMAM G4) dendrimer using the electrostatic layer-by-layer (LbL) technique. Circular dichroism (CD) measurements indicated that the immobilized CCD preserved the same conformation as in solution. The thickness of the very first CCD layers in the LbL films was estimated at ca. 3.6nm, as revealed by surface plasmon resonance (SPR). PAMAM/CCD 10-bilayer films were employed in detecting diluted catechol solutions using either an optical or electrical approach. Due to the mild immobilization conditions employed, especially regarding the pH and ionic strength of the dipping solutions, CCD remained active in the films for periods longer than 3 weeks. The optical detection comprised absorption experiments in which the formation of cis–cis muconic acid, resulting from the reaction between CCD and catechol, was monitored by measuring the absorbance at 260nm after film immersion in catechol solutions. The electrical detection was carried out using LbL films deposited onto gold-interdigitated electrodes immersed in aqueous solutions at different catechol concentrations. Using impedance spectroscopy in a broad frequency range (1Hz–1kHz), we could detect catechol in solutions at concentrations as low as 10−10 M. [Copyright &y& Elsevier]

Abstract: A novel computer approach for in silico molecular modification was here developed and applied to the bacterial enzyme naphthalene 1,2-dioxygenase. A complete set of small deletions was obtained modifying the crystal structure file of the enzyme dimer form, therefore conformational analysis and substrate interaction simulations methods were performed to describe molecule behavior related to different levels of modification. The analysis of interaction zones between all dimers of the examer structure permitted to extend these evaluations to the natural form present on bacterial cells. Four candidates for the biosynthesis of shorter molecules were individuated this way. [Copyright &y& Elsevier]

The article describes the capability of an isolated Candida albicans TL3 to degrade phenol at large concentration. In decontamination of a polluted environment, the study considers biodegradation as an effective method. It found microorganisms including bacteria, yeasts, algae, and aquatic fungi to degrade phenol at various concentrations. It also evaluates the efficiency of candida albicans TL3 to treat waste water from a factory producing phenolic resin.

Abstract: Two kinds of chlorocatechol 1,2-dioxygenase (CCD), TfdC and TfdC2 were detected in Sphingomonas sp. strain TFD44. These two CCDs could be simultaneously synthesized in TFD44 during its growth with 2,4-D as the sole carbon and energy sources. The apparent subunit molecular masses of TfdC and TfdC2 estimated by SDS–PAGE analysis were 33.8 and 33.1kDa, respectively. The genes encoding the two CCDs were cloned and expressed in Escherichia coli. The two purified CCDs showed broad substrate specificities but had different specificity patterns. TfdC showed the highest specificity constant for 3-chlorocatechol and TfdC2 showed the highest specificity constant for 3,5-dichlorocatechol. The substrate specificity difference seemed to correlate with the alternation of amino acid supposed to be involved in the interaction with substrates. Whereas phylogenetic analysis indicated that the CCDs of Sphingomonas constitute a distinctive group among Gram-negative bacteria, TfdC and TfdC2 of TFD44 have divergently evolved in terms of their substrate specificity. [Copyright &y& Elsevier]

w. dong, p. eichhorn, s. radajewski, d. schleheck, k. denger, t.p. knepper, j.c. murrell and a.m. cook. 2004. The aims were to test whether Parvibaculum lavamentivoransT degraded commercial linear alkylbenzenesulphonate (LAS) surfactant via ω-oxygenation and β-oxidation to sulphophenylcarboxylates (SPCs), whether the organism was widespread and reisolable, and whether the degradative community used the 4-sulphocatechol 1,2-dioxygenase to cleave the aromatic ring from LAS. Heterotrophic P. lavamentivoransT converted LAS (side chain length C10–C13) to SPCs (C4–C13), α, β-unsaturated SPCs (C4–C13) and sulphophenyldicarboxylates (SPdCs) (at least C8–C12). Identifications came from high performance liquid chromatography (HPLC) separation, an electrospray interface and mass spectrometry. No evidence for other paths was found. The degradation of LAS in trickling filters inoculated with environmental samples always showed transient SPC intermediates (HPLC) and the presence of the P. lavamentivorans morphotype in the community. One new isolate was obtained. A community able to mineralize LAS contained 4-sulphocatechol-1,2-dioxygenase at high specific activity. Parvibaculum lavamentivoransT degrades commercial LAS via ω-oxygenation, oxidation and chain shortening through β-oxidation to yield a wide range of SPCs. The latter are degraded in bacterial communities which contain organisms like P. lavamentivorans, and which utilize sulphocatechol dioxygenase for ring cleavage. There is one widespread pathway to degrade LAS. Any traces of LAS and larger amounts of SPCs in the effluent from sewage works are exposed to degradative organisms in acclimated and pristine environments. These degradative reactions can now be studied in pure cultures. [ABSTRACT FROM AUTHOR]

Background: Halogenated aromatic compounds are more resistant to microbial degradation than non-halogenated aromatic compounds. Microbial degradation of sodium benzoate in the presence of sodium 3-chlorobenzoate is of interest. The ability to degrade aromatic compounds is largely determined by the substrate specificity of the first enzyme that initiates degradation, namely, benzoate 1,2-dioxygenase for benzoate degradation, and 3-chlorobenzoate 1,2-dioxygenase for 3-chlorobenzoate degradation. In this study, the perspective of immobilized cells of Rhodococcus opacus 1CP actinobacterium for degradation of benzoate and 3-chlorobenzoate was explored., Methods: The biosensor approach (a membrane microbial sensor based on immobilized cells of Rhodococcus opacus 1CP and the Clark-type oxygen electrode as a transducer) was applied to evaluate the actinobacterial cells' responses to benzoate and 3-chlorobenzoate in the absence of both enzymes, benzoate 1,2-dioxygenase and 3-chlorobenzoate 1,2-dioxygenase, or in the presence of one of the said enzymes., Results: Data obtained show that 1CP actinobacterium possessed a constitutive system for the transport of benzoate and 3-chlorobenzoate into culture cells. The affinity of the transport system for benzoate was higher than that for 3-chlorobenzoate. Moreover, adaptation to one substrate did not preclude the use of the second substrate. Probably, porins facilitated the penetration of benzoate and 3-chlorobenzoate into 1CP cells. Analyzing V vs . S dependencies, negative cooperativity was found, when benzoate 1,2-dioxygenase bound substrate (3-chlorobenzoate), while positive cooperativity was determined at benzoate binding. The observed difference could be associated with the presence of at least two systems of 3-chlorobenzoate transport into actinobacterial cells and allosteric interaction of active sites of benzoate 1,2-dioxygenase in the presence of 3-chlorobenzoate., Conclusions: The membrane microbial sensor based on immobilized Rhodococcus opacus 1CP cells could be useful as a perspective tool for comparative evaluation of enzymes of complex structure such as benzoate- and 3-chlorobenzoate 1,2-dioxygenase., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

The gene of catechol 1, 2-dioxygenase was identified and cloned from the genome of Oceanimonas marisflavi 102-Na3. The protein was expressed in Escherichia coli BL21 (DE3) and purified to homogeneity of a dimer with molecular mass of 69.2 kDa. The enzyme was highly stable in pH 6.0–9.5 and below 45 °C and exhibited the maximum activity at pH 8.0 and 30 °C. Being the first characterized intradiol dioxygenase from marine bacteria Oceanimonas sp., the enzyme showed catalytic activity for catechol, 3-methylcatechol, 4-methylcatechol, 3-chlorocatechol, 4-chlorocatechol and pyrogallol. For catechol, K m and V max were 11.2 μM and 13.4 U/mg of protein, respectively. The enzyme also showed resistance to most of the metal ions, surfactants and organic solvents, being a promising biocatalyst for biodegradation of aromatic compounds in complex environments. • A catechol 1,2-dioxygnase from Oceanimonas marisflavi 102-Na3 was expressed. • The enzyme was purified 35.3-fold with a yield of 46.1%. • The enzyme exhibited the maximum activity at pH 8.0 and 30 °C. • The enzyme showed resistance to most tested metal ions, surfactants and organic solvents. [ABSTRACT FROM AUTHOR]

Gentisate 1,2-dioxygenase from the extreme halophile Haloferax sp. D1227 ( Hf. D1227) was purified using a three-step procedure. The enzyme was found to be a homotetramer of 42 000 ± 1000 Da subunits, with a native molecular weight of 174 000 ± 6000 Da. The optimal salt concentration, temperature, and pH for enzyme activity were 2 M KCl or NaCl, 45°C, and pH 7.2, respectively. The gene encoding Hf. D1227 gentisate 1,2-dioxygenase was cloned, sequenced, and expressed in Haloferax volcanii. The deduced amino acid sequence exhibited a 9.2% excess acidic over basic amino acids typical of halophilic enzymes. Four novel histidine clusters and a possible extradiol dioxygenase fingerprint region were identified. [ABSTRACT FROM AUTHOR]

Alcaligenes eutrophus CH34 used benzoate as a sole source of carbon and energy, degrading it through the 3-oxoadipate pathway. All the enzymes required for this degradation were shown to be encoded by chromosomal genes. Catechol 1,2-dioxygenase activity was induced by benzoate, catechol, 4-chlorocatechol, and muconate. The enzyme is most likely a homodimer, with an apparent molecular weight of 76,000 ± 500. According to several criteria, its properties are intermediate between those of catechol 1,2-dioxygenases (CatA) and chlorocatechol 1,2-dioxygenases (ClcA). The determined K for catechol is the lowest among known catechol and chlorocatechol dioxygenases. Similar K values were found for para-substituted catechols, although the catalytic constants were much lower. The catechol 1,2-dioxygenase from strain CH34 is unique in its property to transform tetrachlorocatechol; however, excess substrate led to a marked reversible inhibition. Some meta- and multi-substituted catechols behaved similarly. The determined K (or K ) values for para- or meta-substituted catechols suggest that the presence of an electron-withdrawing substituent at one of these positions results in a higher affinity of the enzyme for the ligand. Results of studies of recognition by the enzyme of various nonmetabolised aromatic compounds are also discussed. [ABSTRACT FROM AUTHOR]