The phs gene and hydrogen sulfide production by Salmonella typhimurium

Clark, Marta A.; Barrett, Ericka L.

doi:10.1128/jb.169.6.2391-2397.1987

Cited by 56 publications

(56 citation statements)

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“…We had hypothesized that sulfite reduction performed by cysI and cysJ mutants was the activity of a dissimilatory enzyme responsible for H2S production from sulfite in complex media. In fact, detectable H2S production from sulfite also requires a low oxidation-reduction potential, as indicated by the location of the zone of blackening in H2S detection tubes (8) and the absence of nitrate (8) and nitrite (Barrett, unpublished findings). Furthermore, H2S production from sulfite is more vigorous in complex media than in defined solid media lacking cysteine (M. A. Clark and E. L. Barrett, unpublished findings).…”

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confidence: 99%

“…typhimurium also produces H2S from thiosulfate, a property that is much more widespread among members of the Enterobacteriaceae than is the ability to produce it from sulfite (3). Previous tests of H2S production from sulfite as compared with its production from thiosulfate (8) demonstrated that these two processes proceed via different enzy-* Corresponding author. matic pathways: a fermentable sugar is required for production of H2S from sulfite, but glucose represses its production from thiosulfate, menaquinone mutants and molybdenum incorporation mutants produce H2S from sulfite but not from thiosulfate, and siroheme mutants retain the ability to reduce thiosulfate to H2S.…”

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“…matic pathways: a fermentable sugar is required for production of H2S from sulfite, but glucose represses its production from thiosulfate, menaquinone mutants and molybdenum incorporation mutants produce H2S from sulfite but not from thiosulfate, and siroheme mutants retain the ability to reduce thiosulfate to H2S. Other qualitative tests (8) indicated that both pathways for H2S accumulation are excluded from the cysteine biosynthetic regulon; they are not negatively regulated by cysteine, the corepressor of the cysteine biosynthetic enzymes (19), or by the absence of the cysB gene product, which is necessary for induction of the biosynthetic pathway (5,16).…”

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Characterization of anaerobic sulfite reduction by Salmonella typhimurium and purification of the anaerobically induced sulfite reductase

1989

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Mutants of Salmonella typhimurium that lack the biosynthetic sulfite reductase (cysI and cysJ mutants) retain the ability to reduce sulfite for growth under anaerobic conditions (E. L. Barrett and G. W. Chang, J. Gen. Microbiol., 115:513-516, 1979). Here we report studies of sulfite reduction by a cysI mutant of S. typhimurium and purification of the associated anaerobic sulfite reductase. Sulfite reduction for anaerobic growth did not require a reducing atmosphere but was prevented by an argon atmosphere contaminated with air (<0.33%). It was also prevented by the presence of 0.1 mM nitrate, which argues against a strictly biosynthetic role for anaerobic sulfite reduction. Anaerobic growth in liquid minimal medium, but not on agar, was found to require additions of trace amounts (lo-7 M) of cysteine. Spontaneous mutants that grew under the argon contaminated with air also lost the requirement for 10-7 M cysteine for anaerobic growth in liquid. A role for sulfite reduction in anaerobic energy generation was contraindicated by the findings that sulfite reduction did not improve cell yields, and anaerobic sulfite reductase activity was greatest during the stationary phase of growth. Sulfite reductase was purified from the cytoplasmic fraction of the anaerobically grown cysI mutant and was purified 190-fold. The most effective donor in crude extracts was NADH. NADPH and methyl viologen were, respectively, 40 and 30% as effective as NADH. Oxygen reversibly inhibited the enzyme. Two highmolecular-weight proteins separated by gel filtration (Mr 360,000 and 490,000, respectively) were required for maximal activity with NADH. Indirect evidence, including in vitro complementation experiments with a cysG mutant extract, suggested that the 3609000-Mr component contains siroheme and is the terminal reductase.This component was further purified to near homogeneity and was found to consist of a single subunit of molecular weight 67,500. The anaerobic sulfite reductase showed some resemblance to the biosynthetic sulfite reductase, but apparently it has a unique, as yet unidentified function.Although much is known about sulfite reduction by the sulfate-reducing bacteria (1, 23, 28), very little is known about the anaerobic production of H2S from sulfite by members of the family Enterobacteriaceae. The ability to perform this reaction is routinely used in diagnostic laboratories to differentiate Salmonella species (H2S positive) from Escherichia coli (H2S negative). We have hypothesized that the enzymes involved may explain the observation that cysI and cysJ (biosynthetic sulfite reductase) mutants of S. typhimurium behave as prototrophs under anaerobic conditions (2), whereas E. coli cysI and cysJ mutants are auxotrophs under both aerobic and anaerobic conditions (E. L. Barrett, unpublished findings). Like E. coli, S. typhimurium mutants defective in cysG, which is required for synthesis of the siroheme prosthetic group (25), do not produce H2S from sulfite and do not behave as prototrophs under anaerobic growth conditions. The...

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Section: Resultsmentioning

confidence: 99%

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Characterization of anaerobic sulfite reduction by Salmonella typhimurium and purification of the anaerobically induced sulfite reductase

1989

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“…However, in S. typhimurium, but not E. coli, anaerobiosis suppresses the auxotrophy of cysI or cysJ mutants (2). Salmonella species, but not E. coli, are known to reduce sulfite to hydrogen sulfide (5,19). This reduction appears to be dissimilatory rather than assimilatory, because it is negatively regulated by the availability of the electron acceptors oxygen and nitrate rather than by the availability of cysteine (5,11).…”

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“…Salmonella species, but not E. coli, are known to reduce sulfite to hydrogen sulfide (5,19). This reduction appears to be dissimilatory rather than assimilatory, because it is negatively regulated by the availability of the electron acceptors oxygen and nitrate rather than by the availability of cysteine (5,11). We have hypothesized that the dissimilatory sulfite reductase activity may be the explanation for the cysI and cysJ mutant anaerobic prototrophy.…”

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