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The ponA Gene of Enterococcus faecalis JH2-2 Codes for a Low-Affinity Class A Penicillin-Binding Protein. Colette Duez, 2004.A soluble derivative of the Enterococcus faecalis JH2-2 class A PBP1 (*PBP1) was overproduced and purified . It exhibited a glycosyltransferase activity on the Escherichia coli 14C-labeled lipid II precursor . As a DD- peptidase, it could hydrolyze thiolester substrates with efficiencies similar to those of other class A penicillin-binding proteins (PBPs) and bind ß-lactams, but with k2/K (a parameter accounting for the acylation step efficiency) values characteristic of penicillin-resistant PBPs . Network of Hydrogenase Maturation in Escherichia coli: Role of Accessory Proteins HypA and HybF. Michaela Hube, 2002.We have studied the roles of the auxiliary protein HypA and of its homolog HybF in hydrogenase maturation . A mutation in hypA leads to the nearly complete blockade of maturation solely of hydrogenase 3 whereas a lesion in hybF drastically but not totally reduces maturation and activity of isoenzymes 1 and 2 . The residual level of matured enzymes in the hybF mutant was shown to be due to the function of HypA; HybF, conversely, was responsible for a minimal residual activity of hydrogenase 3 in the mutant hypA strain . Accordingly, a hypA  hybF double mutant was completely blocked in the maturation process . However, the inclusion of high nickel concentrations in the medium could restore limited activity of all three hydrogenases . The results of this study and of previous work (M . Blokesch, A . Magalon, and A . Böck, J . Bacteriol . 189:2817-2822, 2001) show that the maturation of the three functional hydrogenases from Escherichia coli is intimately connected via the activity of proteins HypA and HypC and of their homologs HybF and HybG, respectively . The results also support the suggestion of Olson et al . (J . W . Olson, N . S . Mehta, and R . J . Maier, Mol . Microbiol . 39:176-182, 2001) that HypA cooperates with HypB in the insertion of nickel into the precursor of the large hydrogenase subunit . Whereas HypA is predominantly involved in the maturation of hydrogenase 3, HybF takes over its function in the maturation of isoenzymes 1 and 2 .
mRNA Differential Display in a Microbial Enrichment Culture: Simultaneous Identification of Three Cyclohexanone Monooxygenases from Three Species. Patricia C. Brzostowicz, 2003.mRNA differential display has been used to identify cyclohexanone oxidation genes in a mixed microbial community derived from a wastewater bioreactor . Thirteen DNA fragments randomly amplified from the total RNA of an enrichment subculture exposed to cyclohexanone corresponded to genes predicted to be involved in the degradation of cyclohexanone . Nine of these DNA fragments are part of genes encoding three distinct Baeyer-Villiger cyclohexanone monooxygenases from three different bacterial species present in the enrichment culture . In Arthrobacter sp . strain BP2 and Rhodococcus sp . strain Phi2, the monooxygenase is part of a gene cluster that includes all the genes required for the degradation of cyclohexanone, while in Rhodococcus sp . strain Phi1 the genes surrounding the monooxygenase are not predicted to be involved in this degradation pathway but rather seem to belong to a biosynthetic pathway . Furthermore, in the case of Arthrobacter strain BP2, three other genes flanking the monooxygenase were identified by differential display, demonstrating that the repeated sampling of bacterial operons shown earlier for a pure culture (D . M . Walters, R . Russ, H . Knackmuss, and P . E . Rouvière, Gene 273:305-315, 2001) is also possible for microbial communities . The activity of the three cyclohexanone monooxygenases was confirmed and characterized following their expression in Escherichia coli . Genes Involved in the Biosynthesis of Photosynthetic Pigments in the Purple Sulfur Photosynthetic Bacterium Thiocapsa roseopersicina. Aacute;kos T. Kovács, 2003.A pigment mutant strain of the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina BBS was isolated by plasposon mutagenesis . Nineteen open reading frame, most of which are thought to be genes involved in the biosynthesis of carotenoids, bacteriochlorophyll, and the photosynthetic reaction center, were identified surrounding the plasposon in a 22-kb-long chromosomal locus . The general arrangement of the photosynthetic genes was similar to that in other purple photosynthetic bacteria; however, the locations of a few genes occurring in this region were unusual . Most of the gene products showed the highest similarity to the corresponding proteins in Rubrivivax gelatinosus . The plasposon was inserted into the crtD gene, likely inactivating crtC as well, and the carotenoid composition of the mutant strain corresponded to the aborted spirilloxanthin pathway . Homologous and heterologous complementation experiments indicated a conserved function of CrtC and CrtD in the purple photosynthetic bacteria . The crtDC and crtE genes were shown to be regulated by oxygen, and a role of CrtJ in aerobic repression was suggested .
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