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The transcriptional regulator PecS from Pectobacterium atrosepticum senses both oxidants and ligands (LB233)
Author(s) -
Deochand Dinesh,
Grove Anne
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.lb233
Subject(s) - pectobacterium , pectobacterium carotovorum , chemistry , erwinia , microbiology and biotechnology , promoter , biochemistry , psychological repression , virulence , proteases , gene , enzyme , biology , gene expression
Pectobacterium atrosepticum (erstwhile Erwinia carotovora ) is one of the top phytopathogens, responsible for soft rot in potato. The pathogenicity of this bacterium is mainly characterized by secretion of cell wall degrading enzymes, for instance pectinases, cellulases and proteases. It has been shown that PecS, a ligand‐responsive MarR family transcription factor, controls expression of the pectinase genes as well as global virulence in the related bacterium E. chrysanthemi (now D. dadantii ). PecS specifically binds to the promoter region of PecS and PecM genes leading to repression of both. PecM is responsible for effluxing blue pigment i.e., indigoidine, which is instrumental in neutralizing ROS, produced by the plant as a defense mechanism. By EMSA we show that P. atrosepticum PecS binds to the intergenic region of PecS and PecM with K d = 1.0 ± 0.1 nM. We speculate that oxidants can attenuate DNA binding by disulfide bond formation between redox‐active cysteines at the dimer interface in PecS, as evidenced by SDS PAGE analysis, which demonstrates that in presence of organic and inorganic peroxides, PecS forms dimers and multimers. Additionally, thermal shift assay corroborates that there are structural changes in the protein since T m of PecS (~50 °C) is significantly reduced in presence of oxidants or ligands. Hence, we propose that PecS modulates global virulence by sensing oxidants in addition to ligands.