Differential role of ferritins in iron metabolism and virulence of the plant pathogenic bacterium Erwinia chrysanthemi 3937. - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Accéder directement au contenu
Article Dans Une Revue Journal of Bacteriology Année : 2007

Differential role of ferritins in iron metabolism and virulence of the plant pathogenic bacterium Erwinia chrysanthemi 3937.

Résumé

During infection the phytopathogenic enterobacterium E. chrysanthemi has to cope with iron limiting conditions and production of reactive oxygen species by plant cells. Previous studies have shown that a tight control of the bacterial intracellular iron content is necessary for full virulence. E. chrysanthemi genome possesses two loci that could be devoted to iron storage: the bfr gene encoding a haem-containing bacterioferritin and the ftnA gene coding for a paradigmatic ferritin. To assess the role of these proteins in the physiology of this pathogen, we constructed ferritin deficient mutants by reverse genetics. Unlike the bfr mutant, the ftnA mutant had increased sensitivity to iron deficiency and to redox stress conditions. Interestingly, the bfr ftnA mutant displayed an intermediate phenotype for the sensitivity to these stresses. Whole cell analysis by M?auer spectrocopy showed that the main iron storage protein is FtnA and that there is an increase in the ferrous/ferric iron ratio in the ftnA and bfr ftnA mutants. We found that the ftnA gene expression is positively controlled by iron and the transcriptional repressor Fur via the small antisens RNA RyhB. bfr gene expression is induced at the stationary phase of growth. The sigmaS transcriptional factor is necessary for this control. Pathogenicity tests showed that the FtnA ferritin and the Bfr bacterioferritin contribute differentialy to the virulence of E. chrysanthemi depending on the host indicating the importance of a perfect control of iron homeostasis in this bacterial species during infection.

Domaines

Bactériologie

Dates et versions

hal-00206061 , version 1 (16-01-2008)

Identifiants

Citer

Aïda Boughammoura, Berthold F Matzanke, Lars Böttger, Sylvie Reverchon, Emmanuel Lesuisse, et al.. Differential role of ferritins in iron metabolism and virulence of the plant pathogenic bacterium Erwinia chrysanthemi 3937.. Journal of Bacteriology, 2007, 190 (5), pp.1518-1530. ⟨10.1128/JB.01640-07⟩. ⟨hal-00206061⟩
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