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Differential accumulation of Salmonella [Cu, Zn] superoxide dismutases SodCI and SodCII in intracellular bacteria: correlation with their relative contribution to pathogenicity
Author(s) -
Uzzau Sergio,
Bossi Lionello,
FigueroaBossi Nara
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03145.x
Subject(s) - biology , superoxide dismutase , salmonella , bacteria , salmonella enterica , microbiology and biotechnology , intracellular , intracellular parasite , innate immune system , pathogenicity island , mutant , gene , reactive oxygen species , epitope , enterobacteriaceae , immune system , enzyme , escherichia coli , genetics , biochemistry , antigen
Summary Most Salmonella enterica strains have two peri‐plasmic [Cu, Zn] superoxide dismutases, SodCI and SodCII, encoded by prophage and chromosomal genes respectively. Both enzymes are thought to play a role in Salmonella pathogenicity by intercepting reactive oxygen species produced by the host's innate immune response. To examine the apparent redundancy, we have compared the levels of epitope‐tagged SodCI and SodCII proteins in bacteria growing in vitro , as well as inside tissue culture cells and in mouse tissues. Concomitantly, we have measured the abilities of mutants of either or both sodC genes to proliferate in infected mice in competition assays. Our results show a striking variation in the relative abundance of the two proteins in different environments. In vitro , both proteins accumulate when bacteria enter stationary phase; however, the increase is much sharper and conspicuous for SodCII than for SodCI. In contrast, SodCI vastly predominates in intracellular bacteria where SodCII levels are negligible. In agreement with these findings, most, if not all, of the contribution of [Cu, Zn] superoxide dismutase activity to murine salmonellosis can be ascribed to the SodCI protein. Overall the results of this work suggest that the duplicate sodC genes of Salmonella have evolved to respond to different sets of conditions encountered by bacteria inside the host and in the environment.