title: Modulation of Mycobacterium tuberculosis proliferation by MtrA, an essential two-component response regulator.
abstract: Paired two-component regulatory systems consisting of a sensor kinase and a response regulator are the major means by which bacteria sense and respond to different stimuli. The role of essential response regulator, MtrA, in Mycobacterium tuberculosis proliferation is unknown. We showed that elevating the intracellular levels of MtrA prevented M. tuberculosis from multiplying in macrophages, mice lungs and spleens, but did not affect its growth in broth. Intracellular trafficking analysis revealed that a vast majority of MtrA overproducing merodiploids were associated with lysosomal associated membrane protein (LAMP-1) positive vacuoles, indicating that intracellular growth attenuation is, in part, due to an impaired ability to block phagosome-lysosome fusion. A merodiploid strain producing elevated levels of phosphorylation-defective MtrA (MtrA(D53N)) was partially replicative in macrophages, but was attenuated in mice. Quantitative real-time PCR analyses revealed that expression of dnaA, an essential replication gene, was sharply upregulated during intramacrophage growth in the MtrA overproducer in a phosphorylation-dependent manner. Chromatin immunoprecipitation using anti-MtrA antibodies provided direct evidence that MtrA regulator binds to dnaA promoter in vivo indicating that dnaA promoter is a MtrA target. Simultaneous overexpression of mtrA regulator and its cognate mtrB kinase neither inhibited growth nor sharply increased the expression levels of dnaA in macrophages. We propose that proliferation of M. tuberculosis in vivo depends, in part, on the optimal ratio of phosphorylated to non-phosphorylated MtrA response regulator.
authors.affiliation: Biomedical Research, The University of Texas Health Center at Tyler, 11937 U.S. Hwy @271, Tyler, TX 75708-3154, USA.
authors.forename: Marek
authors.initials: M
authors.lastname: Fol
authors.forename: Ashwini
authors.initials: A
authors.lastname: Chauhan
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Nair
authors.forename: Erin
authors.initials: E
authors.lastname: Maloney
authors.forename: Meredith
authors.initials: M
authors.lastname: Moomey
authors.forename: Chinnaswamy
authors.initials: C
authors.lastname: Jagannath
authors.forename: Murty V V S
authors.initials: MV
authors.lastname: Madiraju
authors.forename: Malini
authors.initials: M
authors.lastname: Rajagopalan
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008168:Lung / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity; D010766:Phosphorylation; D015398:Signal Transduction; D013154:Spleen / Q000382:microbiology
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; C100938:MtrA protein, Bacteria