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Control of the Ralstonia solanacearum Type III secretion system (Hrp) genes by the global virulence regulator PhcA
Author(s) -
Genin Stéphane,
Brito Belen,
Denny Timothy P.,
Boucher Christian
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.02.058
Subject(s) - ralstonia solanacearum , virulence , biology , mutant , quorum sensing , gene , microbiology and biotechnology , regulator , genetics , secretion , pathogen , biochemistry
Expression of several virulence factors in the plant pathogen bacterium Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA. We provide genetic evidence that PhcA also represses the expression of hrp genes that code for the Type III protein secretion system, a major pathogenicity determinant in this bacterium. The repression of hrp genes in complete medium is relieved in a phcA mutant and two distinct signals, a quorum‐sensing signal and complex nitrogen sources, appear to trigger this PhcA‐dependent repression. This control of hrp gene expression by PhcA is realized at the level of the HrpG regulatory protein.