ABSTRACT
Quantitative side-chain torsion angle χ(1) determinations of phenylalanine residues in Desulfovibrio vulgaris flavodoxin are carried out using exclusively the correlation between the experimental vicinal coupling constants and theoretically determined Karplus equations. Karplus coefficients for nine vicinal coupling related with the torsion angle χ(1) were calculated using the B3LYP functional and basis sets of different size. Optimized χ(1) angles are in outstanding agreement with those previously reported by employing x ray and NMR measurements.
Subject(s)
Desulfovibrio vulgaris/chemistry , Flavodoxin/chemistry , Phenylalanine/chemistry , Quantum Theory , Magnetic Resonance SpectroscopyABSTRACT
Desulfovibrio vulgaris subsp. oxamicus (type strain, DSM 1925(T)) was found to use nitrate as a terminal electron acceptor, the latter being reduced to ammonium. Phylogenetic studies indicated that strain DSM 1925(T) was distantly related to the type strain of Desulfovibrio vulgaris (95.4 % similarity of the small-subunit rRNA gene) and had as its closest phylogenetic relatives two other nitrate- and sulfate-reducing bacteria, namely Desulfovibrio termitidis (99.4 % similarity) and Desulfovibrio longreachensis (98.4 % similarity). Additional experiments were conducted to characterize better strain DSM 1925(T). This strain incompletely oxidized lactate and ethanol to acetate. It also oxidized butanol, pyruvate and citrate, but not glucose, fructose, acetate, propionate, butyrate, methanol, glycerol or peptone. The optimum temperature for growth was 37 degrees C (range 16-50 degrees C) and the optimum NaCl concentration for growth was 0.1 % (range 0-5 %). Because of significant genotypic and phenotypic differences from Desulfovibrio termitidis and Desulfovibrio longreachensis, reclassification of Desulfovibrio vulgaris subsp. oxamicus as Desulfovibrio oxamicus sp. nov., comb. nov., is proposed. The type strain is strain Monticello 2(T) (=DSM 1925(T)=NCIMB 9442(T)=ATCC 33405(T)).
Subject(s)
Desulfovibrio vulgaris/classification , Desulfovibrio/classification , Nitrates/metabolism , Sulfates/metabolism , Carbohydrate Metabolism , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Desulfovibrio/genetics , Desulfovibrio/metabolism , Desulfovibrio/physiology , Desulfovibrio vulgaris/genetics , Desulfovibrio vulgaris/metabolism , Desulfovibrio vulgaris/physiology , Genes, rRNA/genetics , Growth Inhibitors/pharmacology , Molecular Sequence Data , Oxidation-Reduction , Peptones/metabolism , Phylogeny , Quaternary Ammonium Compounds/metabolism , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Sodium Chloride/pharmacologyABSTRACT
In an attempt to isolate the superoxide dismutase (SOD) gene from the anaerobic sulfate-reducing bacterium Desulfoarculus baarsii, a DNA fragment was isolated which functionally complemented an Escherichia coli mutant (sodA sodB) deficient in cytoplasmic SODs. This region carries two open reading frames with sequences which are very similar to that of the rbo-rub operon from Desulfovibrio vulgaris. Independent expression of the rbo and rub genes from ptac showed that expression of rbo was responsible for the observed phenotype. rbo overexpression suppressed all deleterious effects of SOD deficiency in E. coli, including inactivation by superoxide of enzymes containing 4Fe-4S clusters and DNA damage produced via the superoxide-enhanced Fenton reaction. Thus, rbo restored to the sodA sodB mutant the ability to grow on minimal medium without the addition of branched amino acids, and growth on gluconate and succinate carbon sources was no longer impaired. The spontaneous mutation rate, which is elevated in SOD-deficient mutants, returned to the wild-type level in the presence of Rbo, which also restored aerobic viability of sodA sodB recA mutants. Rbo from Desulfovibrio vulgaris, but not Desulfovibrio gigas desulforedoxin, which corresponds to the NH2-terminal domain of Rbo, complemented sod mutants. The physiological role of Rbo in sulfate-reducing bacteria is unknown. In E. coli, Rbo may permit the bacterium to avoid superoxide stress by maintaining functional (reduced) superoxide sensitive 4Fe-4S clusters. It would thereby restore enzyme activities and prevent the release of iron that occurs after cluster degradation and presumably leads to DNA damage.
Subject(s)
Desulfovibrio/genetics , Escherichia coli/enzymology , NADH, NADPH Oxidoreductases/genetics , Superoxide Dismutase/metabolism , Amino Acid Sequence , Cloning, Molecular , Culture Media , Desulfovibrio vulgaris/genetics , Escherichia coli/genetics , Escherichia coli/growth & development , Gene Expression , Genetic Complementation Test , Gluconates/metabolism , Glucose/metabolism , Molecular Sequence Data , Mutagenesis , NADH, NADPH Oxidoreductases/chemistry , NADH, NADPH Oxidoreductases/metabolism , Phenotype , Rubredoxins/genetics , Rubredoxins/metabolism , Succinates/metabolism , Succinic Acid , Superoxide Dismutase/genetics , Superoxides/metabolismABSTRACT
Foram utilizadas as técnicas de cromatografia à liquido de alto desempenho (HPLC), análise por raio-X EDAX) e eletroforese em gel de poliacrilamida (SDS-PAGE) na investigaçäo das interaçöes entre vários cátions e lipopolissacarídeo (LPS) extraído da espécie bacteriana Desulfovibrio vulgaris. O LPS demonstrou afinidades variáveis para diferentes íons divalentes. Eletrodiálise removeu a maioria dos íons Fe (II) do LPS e resultou num aumento dos íons Ca. A HPLC e SDS-PAGE demonstraram diferenças na estrutura de LPs isolado de células ricas ou pobres em Fe(II), que indicaram que o Fe(II)