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

摘要: Mutants of Salmonella typhimurium that lack the biosynthetic sulfite reductase (cysI and cysJ mutants) retain ability to reduce for growth under anaerobic conditions (E. L. Barrett G. W. Chang, J. Gen. Microbiol., 115:513-516, 1979). Here we report studies reduction by a cysI mutant S. purification associated reductase. Sulfite did not require reducing atmosphere but was prevented an argon contaminated with air (less than 0.33%). It also presence 0.1 mM nitrate, which argues against strictly role reduction. Anaerobic in liquid minimal medium, on agar, found additions trace amounts (10(-7)M) cysteine. Spontaneous mutants grew lost requirement 10(-7)M cysteine liquid. A energy generation contraindicated findings improve cell yields, activity greatest during stationary phase growth. purified from cytoplasmic fraction anaerobically grown 190-fold. The most effective donor crude extracts NADH. NADPH methyl viologen were, respectively, 40 30% as Oxygen reversibly inhibited enzyme. Two high-molecular-weight proteins separated gel filtration (Mr 360,000 490,000, respectively) were required maximal Indirect evidence, including vitro complementation experiments cysG extract, suggested 360,000-Mr component contains siroheme is terminal This further near homogeneity consist single subunit molecular weight 67,500. showed some resemblance reductase, apparently it has unique, yet unidentified function.