The iron superoxide dismutase of Legionella pneumophila is essential for viability

A. B. Sadosky, J. W. Wilson, Howard M. Steinman, H. A. Shuman

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Legionella pneumophila, the causative agent of Legionnaires' disease, contains two superoxide dismutases (SODs), a cytoplasmic iron enzyme (FeSOD) and a periplasmic copper-zinc SOD. To study the role of the FeSOD in L. pneumophila, the cloned FeSOD gene (sodB) was inactivated with Tn903dIIlacZ, forming a sodB::lacZ gene fusion. By using this fusion, expression of sodB was shown to be unaffected by a variety of conditions, including several that influence sod expression in Escherichia coli: aeration, oxidants, the redox cycling compound paraquat, manipulation of iron levels in the medium, and the stage of growth. A reproducible twofold decrease in sodB expression was found during growth on agar medium containing charcoal, a potential scavenger of oxyradicals, in comparison with growth on the same medium without charcoal. No induction was seen during growth in human macrophages. Additional copies of sodB+ in trans increased resistance to paraquat. Construction of a sodB mutant was attempted by allelic exchange of the sodB::lacZ fusion with the chromosomal copy of sodB. The mutant could not be isolated, and the allelic exchange was possible only if wild-type sodB was present in trans. These results indicate that the periplasmic copper-zinc SOD cannot replace the FeSOD. The data strongly suggest that sodB is an essential gene and that FeSOD is required for the viability of L. pneumophila. In contrast, Sod- mutants of E. coli and Streptococcus mutans grow aerobically and SOD is not required for viability in these species.

Original languageEnglish (US)
Pages (from-to)3790-3799
Number of pages10
JournalJournal of Bacteriology
Volume176
Issue number12
StatePublished - 1994
Externally publishedYes

Fingerprint

Legionella pneumophila
Superoxide Dismutase
Paraquat
Charcoal
Growth
Zinc
Copper
Iron
Escherichia coli
Legionnaires' Disease
Lac Operon
Streptococcus mutans
Gene Fusion
Essential Genes
Oxidants
Agar
Oxidation-Reduction
Macrophages
Enzymes
Genes

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

The iron superoxide dismutase of Legionella pneumophila is essential for viability. / Sadosky, A. B.; Wilson, J. W.; Steinman, Howard M.; Shuman, H. A.

In: Journal of Bacteriology, Vol. 176, No. 12, 1994, p. 3790-3799.

Research output: Contribution to journalArticle

Sadosky, AB, Wilson, JW, Steinman, HM & Shuman, HA 1994, 'The iron superoxide dismutase of Legionella pneumophila is essential for viability', Journal of Bacteriology, vol. 176, no. 12, pp. 3790-3799.
Sadosky, A. B. ; Wilson, J. W. ; Steinman, Howard M. ; Shuman, H. A. / The iron superoxide dismutase of Legionella pneumophila is essential for viability. In: Journal of Bacteriology. 1994 ; Vol. 176, No. 12. pp. 3790-3799.
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