Very little is understood about the physiology of the periplasm. of gram negative bacteria. The presence of CuZnSOD within that compartment in several different species suggests that oxidative damage occurs there. We studied the regulation of sodC, the gene that encodes CuZnSOD, and the phenotypes of sodC mutants to determine its physiological role. We found that sodC is activated by RpoS in stationary phase, is repressed by Fnr and ArcA anaerobically, and is repressed when copper is unavailable. Mutants of sodC in E. coli and S. typhimurium suffer damage during aerobic growth from a cellular source of superoxide. The unknown damage sensitizes the mutants to subsequent challenges with H2O2. This result indicates that there is a role for CuZnSOD other than protection from exogenous superoxide sources. The cellular source of superoxide and its periplasmic target remain unknown.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign