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In Methanocaldococcus jannaschii, methylglyoxal (MG) is required for aromatic amino acid biosynthesis. Previously, the reduction of MG to lactaldehyde in Methanocaldococcus jannaschii cell extracts using either NADPH or F420H2 was demonstrated; however, the enzyme responsible was not identified. Using NADPH as the reductant, the unknown enzyme was purified from cell extracts of Methanocaldococcus jannaschii and determined to be the F420-dependent N5 ,N10-methylenetetrahydromethanopterin reductase (Mer). Here, we report that the recombinantly overexpressed Mer is able to use NADPH and MG ( KM of 1.6 and 1.0 m m, respectively) to produce lactaldehyde. Additionally, Mer does not catalyze the reduction of MG to lactaldehyde in the presence of reduced Fo, the precursor of F420. [ABSTRACT FROM AUTHOR]

ABSTRACT Adenine deaminases (Ade) and hypoxanthine/guanine phosphoribosyltransferases (Hpt) are widely distributed enzymes involved in purine salvage. Characterization of the previously uncharacterized Ade (MJ1459 gene product) and Hpt (MJ1655 gene product) are discussed here and provide insight into purine salvage in Methanocaldococcus jannaschii. Ade was demonstrated to use either Fe(II) and/or Mn(II) as the catalytic metal. Hpt demonstrated no detectable activity with adenine, but was equally specific for hypoxanthine and guanine with a kcat/ KM of 3.2 × 107 and 3.0 × 107 s− 1 M− 1, respectively. These results demonstrate that hypoxanthine and IMP are the central metabolites in purine salvage in M. jannaschii for AMP and GMP production. A conserved cysteine (C127, M. jannaschii numbering) was examined due to its high conservation in bacterial and archaeal homologues. To assess the role of this highly conserved cysteine in M. jannaschii Ade, site-directed mutagenesis was performed. It was determined that mutation to serine (C127S) completely abolished Ade activity and mutation to alanine (C127A) exhibited 10-fold decrease in kcat over the wild type Ade. To further investigate the role of C127, detailed molecular docking and dynamics studies were performed and revealed adenine was unable to properly orient in the active site in the C127A and C127S Ade model structures due to distinct differences in active site conformation and rotation of D261. Together this work illuminates purine salvage in M. jannaschii and the critical role of a cysteine residue in maintaining active site conformation of Ade. Proteins 2016; 84:828-840. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

SUMMARY Unbleached (gray) cotton needle-punched nonwoven (NW) fabrics with 12.5% polypropylene scrim were treated with two phosphate-nitrogen-based flame retardant (FR) formulations, Southern Regional Research Center (SRRC)-1 and SRRC-2. The SRRC-1 formulation contains diammonium phosphate as the FR chemical along with urea and dimethyloldihydroxyethyleneurea. Because a trace amount of formaldehyde was still expected to be released from SRRC-1-treated FR cotton under high heat, it was preferable to eliminate the dimethyloldihydroxyethyleneurea, leading to the revised formulation SRRC-2. It has a higher content of diammonium phosphate and did not use the polyethylene emulsion that was in SRRC-1. Both formulations were of low cost as they were developed at SRRC using industrial grade chemicals. The fabrics were evaluated with a cone calorimeter using three heat flux levels, 20, 30, and 50 kW/m2. On the basis of the overall cone calorimeter results for heat released and ignition times, FR NW fabrics that were treated with SRRC-2 were found to be slightly superior in flammability properties to those treated with the earlier SRRC-1 formulation, but the differences were statistically insignificant. Both preparations were much less flammable than the untreated control cotton NW fabrics. Compared with the untreated NW fabrics, the FR fabrics had higher visible smoke production. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study investigated physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) [5 or 15% by weight (wt)] at 50 wt % of the wood flour (WF). The WPC panels were made from dry-blended WF, polypropylene (PP) with maleic anhydride-grafted PP (2 wt %), and FR powder formulations using a conventional flat-pressing process under laboratory conditions. The water resistance and strength values of the WPC panels were negatively affected by increasing the FR content as compared to the WPC panels without FR. The WPC panels incorporated with zinc borate (ZB) gave an overall best performance in both water resistance and strength values followed by the panels containing magnesium hydroxide (MH) and ammonium polyphosphate (APP). For these three FR's, the best fire resistance as measured in the cone calorimeter was obtained with the 15 wt % APP treatment and then followed by 15 wt % ZB, or 15 wt % MH formulations. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not—the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen-sensitive reactions and cofactors to function in the new oxygen-containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extra- polation to those metabolic pathways occurring in the ast niversal ommon ncestor (LUCA). Some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii are reviewed. [ABSTRACT FROM AUTHOR]

Methanococcus maripaludis is a strictly anaerobic, methane-producing archaeon and facultative autotroph capable of biosynthesizing all the amino acids and vitamins required for growth. In this work, the novel 6-deoxy-5-ketofructose-1-phosphate (DKFP) pathway for the biosynthesis of aromatic amino acids (AroAAs) and p-aminobenzoic acid (PABA) was demonstrated in M. maripaludis. Moreover, PABA was shown to be derived from an early intermediate in AroAA biosynthesis and not from chorismate. Following metabolic labelling with [U-13C]-acetate, the expected enrichments for phenylalanine and arylamine derived from PABA were observed. DKFP pathway activity was reduced following growth with aryl acids, an alternative source of the AroAAs. Lastly, a deletion mutant of aroA′, which encodes the first step in the DKFP pathway, required AroAAs and PABA for growth. Complementation of the mutants by an aroA′ expression vector restored the wild-type phenotype. In contrast, a deletion of aroB′, which encodes the second step in the DKFP pathway, did not require AroAAs or PABA for growth. Presumably, methanococci contain an alternative activity for this step. These results identify the initial reactions of a new pathway for the biosynthesis of PABA in methanococci. [ABSTRACT FROM AUTHOR]

The hyperthermophilic archaeon Methanococcus jannaschii uses several non-canonical enzymes to catalyze conserved reactions in glycolysis and gluconeogenesis. A highly diverged gene from that organism has been proposed to function as a phosphoglycerate mutase. Like the canonical cofactor-independent phosphoglycerate mutase and other members of the binuclear metalloenzyme superfamily, this M. jannaschii protein has conserved nucleophilic serine and metal-binding residues. Yet the substrate-binding residues are not conserved. We show that the genes at M. jannaschii loci MJ0010 and MJ1612 encode thermostable enzymes with phosphoglycerate mutase activity. Phylogenetic analyses suggest that this gene family arose before the divergence of the archaeal lineage. [Copyright &y& Elsevier]

Coenzyme M (CoM; 2-mercaptoethanesulfonic acid) is the terminal methyl carrier in methanogenesis. Methanogenic archaea begin the production of this essential cofactor by sulfonating phosphoenolpyruvate to form 2-phospho-3-sulfolactate. After dephosphorylation, this precursor is oxidized, decarboxylated and then reductively thiolated to form CoM. A thermostable phosphosulfolactate phosphohydrolase (EC 3.1.3.–) catalyzing the second step in CoM biosynthesis, was identified in the hyperthermophilic euryarchaeon Methanococcus jannaschii. The predicted ORF MJ1140 in the genome of M. jannaschii encodes ComB, a Mg2+-dependent acid phosphatase that is specific for 2-hydroxycarboxylic acid phosphate esters. Recombinantly expressed purified ComB efficiently hydrolyzes rac-2-phosphosulfolactate, (S)-2-phospholactate, phosphoglycolate and both enantiomers of 2-phosphomalate. In contrast to previously studied phosphoglycolate phosphatases, ComB has a low pH optimum for activity, a narrow substrate specificity and an amino acid sequence dissimilar to any biochemically characterized protein. Like other phosphatases that function via covalent phosphoenzyme intermediates, ComB can catalyze a transphosphorylation reaction. Homologs of comB are identified in all available cyanobacterial genome sequences and in genomes from phylogenetically diverse bacteria and archaea; most of these organisms lack homologs of other CoM biosynthetic genes. The broad and disparate distribution of comB homologs suggests that the gene has been recruited frequently into new metabolic pathways. [ABSTRACT FROM AUTHOR]