Differences in enzymatic properties allow SodCI but not SodCII to contribute to virulence in Salmonella enterica serovar typhimurium strain 14028

Radha Krishnakumar, Maureen Craig, James A. Imlay, James M. Slauch

Research output: Contribution to journalArticle

Abstract

Salmonella enterica serovar Typhimurium produces two Cu/Zn cofactored periplasmic superoxide dismutases, SodCI and SodCII. While mutations in sodCI attenuate virulence eightfold, loss of SodCII does not confer a virulence phenotype, nor does it enhance the defect observed in a sodCI background. Despite this in vivo phenotype, SodCI and SodCII are expressed at similar levels in vitro during the stationary phase of growth. By exchanging the open reading frames of sodCI and sodCII, we found that SodCI contributes to virulence when placed under the control of the sodCII promoter. In contrast, SodCII does not contribute to virulence even when expressed from the sodCI promoter. Thus, the disparity in virulence phenotypes is due primarily to some physical difference between the two enzymes. In an attempt to identify the unique property of SodCI, we have tested factors that might affect enzyme activity inside a phagosome. We found no significant difference between SodCI and SodCII in their resistance to acid, resistance to hydrogen peroxide, or ability to obtain copper in a copper-limiting environment. Both enzymes are synthesized as apoenzymes in the absence of copper and can be fully remetallated when copper is added. The one striking difference that we noted is that, whereas SodCII is released normally by an osmotic shock, SodCI is "tethered" within the periplasm by an apparently noncovalent interaction. We propose that this novel property of SodCI is crucial to its ability to contribute to virulence in serovar Typhimurium.

Original languageEnglish (US)
Pages (from-to)5230-5238
Number of pages9
JournalJournal of bacteriology
Volume186
Issue number16
DOIs
StatePublished - Aug 1 2004

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Salmonella enterica
Virulence
Copper
Phenotype
Enzymes
Apoenzymes
Periplasm
Phagosomes
Osmotic Pressure
Hydrogen Peroxide
Open Reading Frames
Superoxide Dismutase
Serogroup
Mutation
Acids
Growth

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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Differences in enzymatic properties allow SodCI but not SodCII to contribute to virulence in Salmonella enterica serovar typhimurium strain 14028. / Krishnakumar, Radha; Craig, Maureen; Imlay, James A.; Slauch, James M.

In: Journal of bacteriology, Vol. 186, No. 16, 01.08.2004, p. 5230-5238.

Research output: Contribution to journalArticle

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