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PII, one of the most conserved signal transduction proteins, is believed to be a key player in the coordination of nitrogen assimilation and carbon metabolism in bacteria, archaea, and plants. However, the identity of PII receptors remains elusive, particularly in photosynthetic organisms. Here we used yeast two-hybrid approaches to identify new PII receptors and to explore the extent of conservation of PII signaling mechanisms between eubacteria and photosynthetic eukaryotes. Screening of Synechococcus sp. strain PCC 7942 libraries with PII as bait resulted in identification of N-acetyl glutamate kinase (NAGK), a key enzyme in the biosynthesis of arginine. The integrity of Ser49, a residue conserved in PII proteins from organisms that perform oxygenic photosynthesis, appears to be essential for NAGK binding. The effect of glnB mutations on NAGK activity is consistent with positive regulation of NAGK by PII. Phylogenetic and yeast two-hybrid analyses strongly suggest that there was conservation of the NAGK-PII regulatory interaction in the evolution of cyanobacteria and chloroplasts, providing insight into the function of eukaryotic PII-like proteins.

CTP synthase is encoded by the pyrG gene and catalyzes the conversion of UTP to CTP. A Lactococcus lactis pyrG mutant with a cytidine requirement was constructed, in which [beta]-galactosidase activity in a pyrG-lacLM transcriptional fusion was used to monitor gene expression of pyrG. A 10-fold decrease in the CTP pool induced by cytidine limitation was found to immediately increase expression of the L. lactis pyrG gene. The final level of expression of pyrG is 37-fold higher than the uninduced level. CTP limitation has pronounced effects on central cellular metabolism, and both RNA and protein syntheses are inhibited. Expression of pyrG responds only to the cellular level of CTP, since expression of pyrG has no correlation to alterations in UTP, GTP, and ATP pool sizes. In the untranslated pyrG leader sequence a potential terminator structure can be identified, and this structure is required for regulation of the pyrG gene. It is possible to fold the pyrG leader in an alternative structure that would prevent the formation of the terminator. We suggest a model for pyrG regulation in L. lactis, and probably in other gram-positive bacteria as well, in which pyrG expression is directly dependent on the CTP concentration through an attenuator mechanism. At normal CTP concentrations a terminator is preferentially formed in the pyrG leader, thereby reducing expression of CTP synthase. At low CTP concentrations the RNA polymerase pauses at a stretch of C residues in the pyrG leader, thereby allowing an antiterminator to form and transcription to proceed. This model therefore does not include any trans-acting protein for sensing the CTP concentration as previously proposed for Bacillus subtilis.

Anthranilate (2-aminobenzoate) is an important intermediate in tryptophan metabolism. In order to investigate the degradation of tryptophan through anthranilate by Burkholderia cepacia, several plasposon mutations were constructed of strain DBO1 and one mutant with the plasposon insertion in the anthranilate dioxygenase (AntDO) genes was chosen for further study. The gene sequence obtained from flanking DNA of the plasposon insertion site revealed unexpected information. B. cepacia DBO1 AntDO (designated AntDO-3C) is a three-component Rieske-type [2Fe-2S] dioxygenase composed of a reductase (AndAa), a ferredoxin (AndAb), and a two-subunit oxygenase (AndAcAd). This is in contrast to the two-component (an oxygenase and a reductase) AntDO enzyme from Acinetobacter sp. strain ADP1, P. aeruginosa PAO1, and P. putida P111. AntDO from strains ADP1, PAO1, and P111 are closely related to benzoate dioxygenase, while AntDO-3C is closely related to aromatic hydrocarbon dioxygenases from Novosphingobium aromaticivorans F199 and Sphingomonas yanoikuyae B1 and 2-chlorobenzoate dioxygenase from P. aeruginosa strains 142 and JB2. Escherichia coli cells expressing the functional AntDO-3C genes transform anthranilate and salicylate (but not 2-chlorobenzoate) to catechol. The enzyme includes a novel reductase whose absence results in less efficient transformation of anthranilate by the oxygenase and ferredoxin. AndR, a possible AraC/XyIS-type transcriptional regulator, was shown to positively regulate expression of the andAcAdAbAa genes. Anthranilate was the only effector (of 12 aromatic compounds tested) that was able to induce expression of the genes.

The enzyme phosphodiesterase is purified from the native organism and the recombinant Escherichia coli. It is an 85-kilodalton trimer, exhibits both mono- and diesterase activity, and shows sequence similarity to cyclic AMP phosphodiesterase and cyclic nucleotide phosphodiesterases.

Results demonstrate the secretion of alpha-amylase in Pseudoalteromonas haloplanktis and Psychrobacter sp. strain TAD1. Data indicate that the secretion occurs via two different pathways in these organisms in a physiologic environment.

Research describes the purification of the beta-ribofuranosylaminobenzene 5'-phosphate synthase from Methanosarcina thermophila and identification of the enzyme homologs in archaea and in M. extorquens bacterium. The gene encoding the enzyme is overexpressed in Archaeoglobus gulgidus.

Results reveal that expression of 22 proteins is affected by pH in Escherichia coli cells grown over a range of pHs from acid through base. Also, high-pH induces 3 genes, suggesting that E. coli modulates multiple transporters and amino acid consumption pathways to minimize drastic pH shift of the external conditions.

The relationship of the fts genes to beta-lactamase induction together with a murein transpeptidase PBP2 is investigated. Results reveal that in the cells lacking fts and PBP2(Ts), the cells accumulate corepressor which cannot be displaced by the inducer or inducer is almost nonexistent. Both conditions lead to a high ratio of repressor to inducer preventing induction.

The organization and regulatory mechanism of the arginine dehydrogenase pathway are analyzed using the structural gene, gbuA, for guanidinobutyrase in Pseudomonas aeruginosa PAO1. Research reveals that the LysR-type transcriptional regulator, GbuR, induces the expression of gbuA. Sequence analysis assigns guanidinobutyrase to the arginase/agmatinase family of proteins.

Results show that the GAG lyases, heparinase I, III, and III and chondroitinase AC and B in Flavobacterium increase several-fold by hepA. The hepA gene transcripts start 26 basepairs from hepA's start codon.

Research shows that ggpS gene encodes glucosylglycerol-phosphate synthase involved in glucosylglycerol synthesis and the gene induction occurs upon osmotic upshift with concomitant increase in the tranlation products. However, gene induction in shocked cells is not accompanied by mRNA or protein contents, suggesting two regulatory levels for the synthesis of glucosylglycerol.

Results reveal that ansZ gene encodes L-asparaginase following activation by TnrA in a nitrogen-limited medium. Further, the second L-asparaginase is encoded by the ansA gene, which is induced by asparagine.

Exposure of the anaerobic Bacteroides fragalis bacterium to atmospheric oxygen induces the gene nrdA, which encodes an aerobic-type ribonucleotide reductase. Data indicate that the enzyme may be involved in the supply of deoxyribonucleotides for repairing oxidatively damaged DNA.

The capsule biosynthesis protein CpsB in Streptococcus pneumoniae is a member of the polymerase and histidinol phosphatase family of phosphoesterases. Data suggest that CpsB requires manganese for optimal activity and mutation of the histidine residues inactivates the enzyme.

Results show that the C-terminal region of hemolytic sphingomyelinase of Pseudomonas sp. strain TK4 is important for the hemolytic activity but not essential for the sphingomyelinase activity. In the presence of manganese, the recombinant enzyme hydrolyzes sphingomyelin but not other phospholipids.

Research shows that the gamma-polyglutamic acid in Bacillus subtilis IFO6449 is coded by two of the four genes of the operon contained on a 4.2-kilobase cloned DNA. The protein consists of two subunits. Data suggest that gamma-polyglutamic acid biosynthesis is mediated by polyglutamic acid synthetase.

Research describes the physiologic and genetic basis of L-ascorbate fermentation by Escherichia coli K-12 operon. The operons ula (yif-sga) and yia-sgb code for all the enzymes in the catabolic pathway of L-ascorbate utilization.

Research demonstrates that the Aspergillus nidulans acuF gene encodes a protein very similar to the ATP-dependent phosphoenolpyruvate carboxykinase of other species. Data indicte that the gene is induced by tricarboxylic acid cycle intermediates.

Research demonstrates heterologous production of the Clostridium cellulovorans cellulosome containing the enzymatic subunit EngB with the scaffolding unit, a cellulose binding domain, and two cohesin deomain units. Data indicate that the recombinant EngB cellulosome exhibits a dockerin domain similar to the native protein.

Results indicate that Ralstonia eutropha strain Bo utilize tetrahydrofurfuryl alcohol for growth and synthesize aldehyde dehydrogenases including the aldehyde dehydrogenase 4, whose N-terminal sequence bears similarities to other NAD(P)-dependent aldehyde dehydrogenases.

Research reveals that the actinomycete Amycolatopsis methanolica expresses a ATP-dependent phosphofructokinase when grown on one-carbon compounds as opposed to PP(sub)i-dependent phosphofructokinase induction in glucose grown cells. Results indicate that the two isoenzymes are functionally different and utillize one-carbon and six-carbon substrates, respectively.

Results reveal that starch utilization system of Bacteroides thetaiotaomicron is regulated by a newly discovered regulatory protein, MalR besides the previously characterized SusR. Data show that cells that can not grow on maltose and maltotriose exhibit malR gene, which encodes an alpha-glucosidase that is not regulated by SusR.

Research shows that the reduced GTPase activity of the FtsZ protein mutant FtsZ2 is due to a defect in the catalytic site caused by replacement of aspartic acid to glycine. Data indicte that FtsZ2 is incapable of supporting cell division unless supplemented with FtsZ.

Transposon mutagenesis demonstrates that both fbiA and fbiB genes are required for normal coenzyme F(sub)420-(sup)5,6 synthesis and together they constitute an operon. Data indicate that both the genes function between the intermediate FO and the coenzyme.

Microarray analysis of 271 open reading frame genes that encode metabolic pathway proteins in Pyrococcus furiosus reveals that elemental sulfur or its metabolites regulate transcription of the open reading frame genes. Results suggest that the elemental sulfur reduction is catalyzed by a newly synthesized enzyme system.

Results show that the licC encodes LicC protein that exhibits CTP:phosphocholine cytidylyltransferase activity. Furthermore, LicC participates in the biosynthesis of cell wall constituents involved in the cell separation and pathogenesis.

Results show that at low temperature, pnp gene expression and polynucleotide phosphorylase autocontrol mechanism are linked in Escherichia coli. Data further suggest that at low temperatures mRNA destabilization is less efficient, which leads to an increased expression of the protein.

Research describes purification and characterization of a germination-specific protease from germinating spores of Clostridium perfringens S40. Results show that the protease is encoded by sleC gene and is comprised of 60,57, and 52 kilodalton protein components and is a cysteine-dependent subtilisin-like serine protease as deduced from amino acid sequence analysis.

Results show that the proteolytic system of Lactococcus lactis consists of 16 genes whose transcription is regulated by the peptide availability. Data further reveal that of the 15 promoters involved, transcription of eight promoters is dependent on the peptide content in the medium and that of pepP by carbon source.

Results demonstrate that the fabH gene of the fab gene cluster encodes a ketoacyl synthase III, which is involved in the initiation of fatty acid biosynthesis in Streptomyces coelicolor A3(2).

Results show that ypfP gene encoded diglucosyldiacylglycerol synthase, YpfP, is the only synthase that anchors lipoteichoic acid by providing glycolipid anchor and other free membrane glycolipids in Staphylococcus aureus RN4220.

Research reveals that in Staphylococcus aureus, the superoxide dismutase activity is predominantly of SodA type during all phases of growth and SodM type dismutase manifests under oxidative stress conditions during late exponential and stationary phases of growth. The SodM sequence specifies a 187-amino-acid protein with a 75% homology with SodA.

Results demonstrate that fsrB gene is essential for fsr regulator's functions and the expression of fsrA, fsrB, fsrC, gelE, and sprE promoters is directed by three different promoters. The expression of fsrB and fsrC is dependent on cell density. Two repeats of 7-basepair length regulate fsrB and gelE expression.

Results show that six genes are involved in the synthesis and assembly of D-galactan I and galactosyltransferases mediating polymerization process. Data indicate that WecA, Wbbo, and WbbM galactosyltransferases are sufficient for the D-galactan I synthesis with Wbbo involved in the polymerization process.

Research describes two peptidases in Salmonella enterica serovar Typhimurium that can hydrolyze N-terminal aspartic peptides. Results indicate that Typhimurium enzymes are homologs of Escherichia coli N-terminal isoAsp-hydrolyzing dipeptidase and isoAsp-hydrolyzing peptidase.

This article describes the cloning, sequencing, and mutagenesis of glnD gene encoding uridylyl-transferase in Sinorhizobium meliloti. Data indicate that glnD is cotranscribed with a homologous mviN gene of Salmonella and both genes are localized to the same operon.

Research describes cloning, expression, and characterization of the alr1(sp)+ gene and its encoded product alanine racemase ALR1p of Schizosaccharomyces pombe. Data indicate that alanine racemase mediates D-alanine catabolism in S. pombe and enables growth of S. cerevisiae on D-alanine as a sole nitrogen following heterologous expression of the gene.

Results demonstrate that phenotypic variants of Pseudomonas brassicacearum without extracellular protease and lipase activities are phase variants as revealed by the effect of phase variation on the operon coding for the enzymes.

Results describe genetic and kinetic analyses of a thioredoxin-dependent alkyl hydroperoxide reductase system from Helicobacter pylori. Data indicate that the the enzyme plays a role in protecting the bacterium from oxygen toxicity thereby promoting growth and survival.

Results demonstrate the dependency of alpha-amylase secretion and proper protein folding on the cellular concentration of the lipoprotein PrsA in Bacillus subtilis. Data further sugest that PrsA is required for cell viability and its depletion leads to altered cellular morphology and cell death.

Research describes the identification of two genes, vibD and vibH, of the catechol siderophore vibriobactin gene region, which are essential for vibriobactin biosynthesis. Data show that vibD and vibH encode different enzymes, a phosphopantetheinyl transferase and a peptide synthase, respectively.

Cloning, sequencing, and characterization of a 6-kilo basepair fragment of TW3 DNA, which encodes enzymes of 4-nitrobenzoate catabolism pathway in Pseudomonas putida are presented. The fragment contains five genes, two of which encode the enzymes 4-nitrobenzoate reductase, a reductase-like enzyme, a 4-hydroxylaminobenzoate lyase, and a second lyase-like enzyme.

Results reveal that the starchless mutant of Chlamydomonas reinhardii contain a defective STA6 locus responsible for accumulation of starch and ADP-glucose pyrophosphorylase activity. Data indicate that STA6 locus encodes a 50 kilodalton protein, which exhibits homology to ADP-glucose pyrophosphorylase small-subunit of vascular plants.

In Bacillus sp. strain GL1, xanthan lyase is processed in several steps. It is synthesized as a 99 kDa preproform, then converted to a 97 kDa precursor, and finally into the mature 75 kDa enzyme.

Research describes cloning and sequencing of overlapping fragments from Ralstonia U2 strain spanning a 21.6 kilobase region of the nag genes. Results reveal that the genes encode enzymes involved in the catabolism of gentisate metabolites generated from naphthalene.

Results demonstrate that hvnA and hvnB genes via their respective encoded proteins mediate polyarginine ADP-ribosylation through an NAD+ -glycohydrolase releasing free ADP-ribose in Vibrio fischeri.

Research reveals that a conserved archaeal gene in methanococcus jannaschii represents the shikimate kinase gene, which encodes homoserine kinases of the GHMP-kinase superfamily. Results describe the expression, purification, and characterization of this unique enzyme and phosphorylation of shikimate.

Research reveals that hydrogen sulfide production by the commercial isolates of yeast during fermentation is not due to low sulfur incorporation into organic compounds as indicated by the negative correlation between O-acetylserine/O-acetylhomoserine sulfhydrylase activity and hydrogen sulfide release.

Research describes the construction of an oligonucleotide probe that contains part of the gene encoding catalase-peroxidase to screen the genomic library of Mycobacterium sp. strain PYR-1. Data show that the enzyme is involved in the polycylic aromatic hydrocarbon metabolism of the bacterium as indicated by its induction in pyrene-containing cultures.

Research describes the construction of rhizobial strains with hydrogen-recycling ability using a minitransposon carrying the hydrogen-uptake gene from Rhizobium leguminosarum bv. viciae UPM791. Bacteria containing the reconstructed gene generated high amount of hydrogen that got recycled by nitrogenase of the nodules.