The PecM protein is necessary for the DNA-binding capacity of the PecS repressor, one of the regulators of virulence-factor synthesis in Erwinia chrysanthemi.
The pecS regulatory locus is responsible for the down-expression of many virulence genes in Erwinia chrysanthemi. This locus consists of two genes, pecS and pecM, divergently transcribed. Genetic evidence indicates that the PecM protein modulates the regulatory activity of PecS. Purification and characterization of PecS, expressed either from E. coli, from the wild-type E. chrysanthemi strain or from a pecM mutant, showed that the PecS protein produced in these three genetic backgrounds displays the same biochemical properties. Band-shift assay analysis with the three PecS isoforms confirmed the involvement of the PecM protein in modulating the PecS DNA-binding capacity. Moreover, determination of the Kdapp for operator regions of the PecS protein, produced either by the wild-type E. chrysanthemi or by E. coli, reveals similar affinities. Thus, in E. coli, there is likely to be at least one other PecM-like protein able to cross-react with the E. chrysanthemi PecS protein.
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Laboratoire de Génétique Moléculaire des Microorganismes et des Interactions Cellulaires, CNRS UMR 5577, INSA Lyon, France. lgmm@cismibm.univ-lyon1.fr
Reverchon
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Robert-Baudouy
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Nasser
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology*; D004247:DNA / Q000378:metabolism*; D016974:Dickeya chrysanthemi / Q000737:chemistry* / Q000235:genetics / Q000472:pathogenicity; D008565:Membrane Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000302:isolation & purification / Q000502:physiology*; D014774:Virulence
D001426:Bacterial Proteins; D008565:Membrane Proteins; C088079:PecM protein, Erwinia chrysanthemi; D012097:Repressor Proteins; C088080:pecS protein, Erwinia chrysanthemi; D004247:DNA