The response regulator PmrA is a major regulator of the icm/dot type IV secretion system in Legionella pneumophila and Coxiella burnetii.
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 pmrA deletion mutant, intracellular growth analysis, comparison of gene expression between L. pneumophila wild type and the pmrA 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.
Zusman
Tal
T
Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
Aloni
Gali
G
Halperin
Einat
E
Kotzer
Hani
H
Degtyar
Elena
E
Feldman
Michal
M
Segal
Gil
G
D000595:Amino Acid Sequence; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D019295:Computational Biology; D017124:Conserved Sequence; D016997:Coxiella burnetii / Q000235:genetics / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006801:Humans; D016952:Legionella pneumophila / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D008264:Macrophages / Q000382:microbiology; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D021381:Protein Transport; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C081902:pmrA protein, Bacteria; D001616:beta-Galactosidase