Nutritional Studies of Cysteineless Mutants of Salmonella typhimurium

Clowes, Royston C.

doi:10.1099/00221287-18-1-140

Cited by 32 publications

(11 citation statements)

References 8 publications

(7 reference statements)

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“…or 0.2y0 (w/v) Difco nutrient broth powder. (b) Auxanographic technique (Clowes, 1958). Liquid cultures of organisms grown with limiting amounts of methionine (2pg./ml.)…”

Section: Chemicalsmentioning

confidence: 99%

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Methionine synthesis in Proteus mirabilis

Grabow

Smit

1967

Journal of General Microbiology

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S U M M A R YSixty different isolates of methionineless auxotrophs of Proteus mirabilis were arranged in nine biochemical groups according to their growth responses to methionine or its precursors. These requirements suggested that P. mirabilis possesses a route for methionine biosynthesis which is similar to the pathway operating in Escherichia coli and Salmonella typhimurium. In contrast to findings with the latter organisms syntrophism was not observed between these mutants of P. mirabilis even with sonically disrupted potential feeder strains. Two methionineless auxotrophs of E. coli fed auxotrophs of P. mirabilis which had metabolic blocks earlier in this pathway. These results, which suggested an inability of methionineless auxotrophs of P. mirabilis to accumulate precursors of metabolic blocks, were confirmed by a quantitative comparison of methionine precursors in wild-type and mutant strains of P. mirabilis and E. coli. The presence of S-methylcysteine (SMC) was demonstrated in wild-type and methionineless auxotrophs of P. mirabilis and E. coli. The growth responses of methionineless auxotrophs of P. mirabilis to SMC supported a hypothesis for the participation of this amino acid in the synthesis of methionine via an alternative route.

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“…or 0.2y0 (w/v) Difco nutrient broth powder. (b) Auxanographic technique (Clowes, 1958). Liquid cultures of organisms grown with limiting amounts of methionine (2pg./ml.)…”

Section: Chemicalsmentioning

confidence: 99%

“…This was determined by the following techniques. (a) Parallel streaking (Demerec et al 1955;Smith, 1961;Clowes, 1958). Parallel streaks of mutants were made about 2-3 mm.…”

Section: Chemicalsmentioning

confidence: 99%

Methionine synthesis in Proteus mirabilis

Grabow

Smit

1967

Journal of General Microbiology

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“…However, in E. coli and S. typhimurium much of the work that has resulted in the elucidation of the cysteine biosynthetic pathway has come from the study of cysteine auxotrophs (Clowes, 1958 ;Dreyfuss & Monty, 1963;Jones-Mortimer, 1968 a ; Kredich, 1971).…”

Section: Introductionmentioning

confidence: 98%

Cysteine Biosynthesis in Paracoccus denitrificans

Paraskeva¹,

Whatley²

1980

Microbiology

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Forty cysteine-requiring mutants of Paracoccus denitriJicans were isolated. The growth requirements of these mutants were consistent with sulphite and sulphide being intermediates in the reduction of sulphate to cysteine in P. denitrzjicans. Fourteen were deficient in ATP sulphurylase and/or APS kinase. Of these, twelve were also unable to transport sulphate into the cell, showing that they were pleiotropic, being deficient in at least two and possibly three enzymes of the cysteine biosynthetic pathway.

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“…All previous cysG mutants were isolated as cysteine auxotrophs and were thus defective in synthesis of siroheme (required for sulfite and nitrite reductases) (10,11,16,24,26). Previously, a set of 30 such Salmonella cysG mutants were found to be defective for cobalamin synthesis (B 12 Ϫ ) (16).…”

Section: Isolation Of Cysg Mutants With a Cysmentioning

confidence: 99%

“…In both Escherichia coli and Salmonella typhimurium, cysG mutants were initially identified as cysteine-requiring (Cys Ϫ ) auxotrophs (10,26). These mutants, as well as cysIJ mutants were shown to be defective in reduction of sulfite to sulfide (14), which is required for cysteine biosynthesis.…”

mentioning

confidence: 99%

Evidence that the CysG protein catalyzes the first reaction specific to B12 synthesis in Salmonella typhimurium, insertion of cobalt

Fazzio

Roth

1996

J Bacteriol

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The cysG gene of Salmonella typhimurium is involved in synthesis of both cobalamin (B 12 ) and siroheme (a cofactor required for SO 3 2؊ and NO 2 2؊ reductases). The failure to reduce SO 3 2؊ leads to cysteine auxotrophy, for which the enzyme is named. Although Escherichia coli does not synthesize B 12 de novo, it possesses a very similar CysG enzyme which has been shown to catalyze two methylations (uroporphyrinogen III to precorrin-2), ring oxidation (precorrin-2 to factor II), and iron insertion (factor II to siroheme). In S. typhimurium, precorrin-2 is a precursor of both siroheme and B 12 . All previously known Salmonella cysG mutants are defective in the synthesis of both siroheme and cobalamin. We describe two new classes of cysG mutants that cannot synthesize B 12 but still make siroheme. For class I mutants, exogenous cobalt corrects the B 12 defect but inhibits ability to make siroheme; B 12 synthesis is inhibited by added iron. Class II mutants are unaffected by exogenous cobalt, but their B 12 defect is corrected by derepression of the B 12 biosynthetic genes (cob). We propose that all mutants are defective in insertion of cobalt into factor II and that the Salmonella CysG enzyme normally catalyzes this insertion-the first reaction dedicated to cobalamin synthesis. Although E. coli does not make B 12 , its CysG enzyme has been shown in vitro to insert cobalt into factor II and may have evolved to support B 12 synthesis in some ancestor common to Salmonella species and E. coli.

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Nutritional Studies of Cysteineless Mutants of Salmonella typhimurium

Cited by 32 publications

References 8 publications

Methionine synthesis in Proteus mirabilis

Methionine synthesis in Proteus mirabilis

Cysteine Biosynthesis in Paracoccus denitrificans

Evidence that the CysG protein catalyzes the first reaction specific to B12 synthesis in Salmonella typhimurium, insertion of cobalt

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