Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of proteins necessary for the respiratory reduction of nitrate to dinitrogen is induced in most denitrifying bacteria by a shift to anaerobiosis. A homolog of the fur gene, which encodes a redox-active transcriptional activator in Escherichia coli, was isolated from Pseudomonas stutzeri by using the anr gene of Pseudomonas aeruginosa as the hybridization probe (R. G. Sawers, Mol. Microbiol. 5:1469-1481, 1991). The coding region was located on a 3-kb SmaI fragment. An open reading frame of 735 nucleotides, designated fnrA, had the coding potential for a protein of 244 amino acids (M(r) = 27,089) with 51.2% positional identity to the Fnr protein of E. coli and 86.1% to the Anr protein of P. aeruginosa. The fnrA gene gave a single transcript of 0.85 kb and complemented nitrate-dependent anaerobic growth of an fnr deletion mutant of E. coli. An open reading frame immediately downstream of fnrA encoded adenine phosphoribosyltransferase (EC 2.4.2.7). Mutations in fnrA were generated in vitro by insertional mutagenesis followed by gene replacement. Gene inactivation was shown by loss of the fnrA transcript and detection of an arginine deiminase (EC 3.5.3.6)-negative phenotype in the mutants. However, neither the enzymatic activities nor the levels of anaerobic expression of the respiratory enzymes nitrate reductase (EC 1.7.99.4), nitrate reductase (EC 1.9.3.2), NO reductase (EC 1.7.99.7), and N2O reductase (EC 1.7.99.6) were changed in fnrA mutants versus the P. stutzeri wild type. A promoter-probe vector for Fnr-dependent transcription was activated anaerobically in the fnrA mutants, suggesting the existence of a second Fnr homolog in the same bacterium. The Fnr-binding motifs, apparent in the promoter region of genes encoding denitrification components of P. stutzeri, are likely to be recognized by this second Fnr homolog. Preliminary evidence indicates also the presence of the catabolite activator protein, Crp, in P. stutzeri.
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PMID:Anaerobic control of denitrification in Pseudomonas stutzeri escapes mutagenesis of an fnr-like gene. 822 70

Escherichia coli O157:H7 has an unusually high resistance to acidic environments. Some research has revealed that acid-adapted cells, by exposure to moderately acidic conditions, are more resistant to a subsequent strong acidic challenge or other stress. This study was conducted to understand the protein expression regulation of acid tolerance response (ATR) of a local isolated E. coli O157:H7 TWC01 (TWC01) induced by an acidic environment. TWC01 cells were acid adapted by using hydrochloric acid (HCl) or lactic acid as acidifier to induce ATR. The total proteins of adapted cells were extracted for proteomic analysis and protein identification by matrix-assisted laser desorption ionization quadrupole time-of-flight tandem mass spectrometry (MALDI-Q-TOF MS/MS). Furthermore, the effects of acid adaptation on shiga-like toxin (stx) secretion were examined. Results revealed that acid adaptation depressed stx production of E. coli O157:H7 TWC01 during adaptation and did not improve post-stress toxin production. Image analysis of the gel indicated that numerous proteins were up-regulated and that lactic acid had a greater effect than HCl did (percentages of up-regulated proteins were 57.64 and 35.47%, respectively). Analysis of proteins by mass spectrometry revealed that most of the up-regulated proteins were metabolism-related, including phosphoglycerate kinase (PGK), glutamate decarboxylases alpha and beta (GadA, GadB), adenine phosphoribosyltransferase (APRT), and dihydrodipicolinate synthase (DHDPS). Others were related to translation (e.g., elongation factor Tu, elongation factor G), protein folding (e.g., alkyl hydroperoxide reductase), and membrane proteins (e.g., ompA precursor and ompR). The variation of protein expression showed that acid resistance was induced in TWC01 and was primarily manifested via expression of up-regulated proteins that contribute to increased energy conservation and polypeptide synthesis.
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PMID:Physiological response and protein expression under acid stress of Escherichia coli O157:H7 TWC01 isolated from Taiwan. 1763 Jul 66