Biogenesis of Fe/S proteins and pathogenicity: IscR plays a key role in allowing Erwinia chrysanthemi to adapt to hostile conditions.
The Erwinia chrysanthemi genome is predicted to encode three systems, Nif, Isc and Suf, known to assist Fe/S cluster biogenesis and the CsdAE cysteine desulphurase. Single iscU, hscA and fdx mutants were found sensitive to paraquat and exhibited reduced virulence on both chicory leaves and Arabidopsis thaliana. Depletion of the whole Isc system led to a pleiotropic phenotype, including sensitivity to both paraquat and 2,2'-dipyridyl, auxotrophies for branched-chain amino acids, thiamine, nicotinic acid, and drastic alteration in virulence. IscR was able to suppress all of the phenotypes listed above in a sufC-dependent manner while depletion of the Isc system led to IscR-dependent activation of the suf operon. No virulence defects were found associated with csdA or nifS mutations. Surprisingly, we found that the sufC mutant was virulent against A. thaliana, whereas its virulence had been found altered in Saintpaulia. Collectively, these results lead us to propose that E. chrysanthemi possess the Fe/S biogenesis strategy suited to the physico-chemical conditions encountered in its host upon infection. In this view, the IscR regulator, which controls both Isc and Suf, is predicted to play a major role in the ability of E. chrysanthemi to colonize a wide array of different plants.
Rincon-Enriquez
Gabriel
G
Université de la Méditerranée, Aix-Marseille II, Campus de Luminy 70 rte Léon Lachamp 13009 Marseille, France.
Crété
Patrice
P
Barras
Frédéric
F
Py
Béatrice
B
D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism; D018651:Cichorium intybus / Q000382:microbiology; D002876:Chromosomes, Bacterial / Q000235:genetics; D016974:Dickeya chrysanthemi / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D016680:Genome, Bacterial; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D008957:Models, Genetic; D009154:Mutation; D009876:Operon / Q000235:genetics; D010269:Paraquat / Q000494:pharmacology; D010641:Phenotype; D018515:Plant Leaves / Q000382:microbiology; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D010269:Paraquat