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The response regulator PmrA is a major regulator of the icm / dot type IV secretion system in Legionella pneumophila and Coxiella burnetii
Author(s) -
Zusman Tal,
Aloni Gali,
Halperin Einat,
Kotzer Hani,
Degtyar Elena,
Feldman Michal,
Segal Gil
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05604.x
Subject(s) - legionella pneumophila , coxiella burnetii , biology , regulator , mutant , secretion , microbiology and biotechnology , legionella , gene , response regulator , genetics , bacteria , biochemistry
Summary Legionella pneumophila and Coxiella burnetii have been shown to utilize the icm/dot type IV secretion system for pathogenesis and recently a large number of icm / dot ‐translocated substrates were identified in L. pneumophila . Bioinformatic analysis has revealed that 13 of the genes encoding for L. pneumophila ‐translocated substrates and five of the C. burnetii icm / dot genes, contain a conserved regulatory element that resembles the target sequence of the PmrA response regulator. Experimental analysis which included the construction of a L. pneumophila pmr A deletion mutant, intracellular growth analysis, comparison of gene expression between L. pneumophila wild type and the pmr A mutant, construction of mutations in the PmrA conserved regulatory element, controlled expression studies as well as mobility shift assays, demonstrated the direct relation between the PmrA regulator and the expression of L. pneumophila icm / dot ‐translocated substrates and several C. burnetii icm / dot genes. Furthermore, genomic analysis identified 35 L. pneumophila and 68 C. burnetii unique genes that contain the PmrA regulatory element and few of these genes from L. pneumophila were found to be new icm / dot ‐translocated substrates. Our results establish the PmrA regulator as a fundamental regulator of the icm / dot type IV secretion system in these two bacteria.