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Modulation of Mycobacterium tuberculosis proliferation by MtrA, an essential two‐component response regulator
Author(s) -
Fol Marek,
Chauhan Ashwini,
Nair Naveen K.,
Maloney Erin,
Moomey Meredith,
Jagannath Chinnaswamy,
Madiraju Murty V. V. S.,
Rajagopalan Malini
Publication year - 2006
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.1365-2958.2006.05137.x
Subject(s) - biology , response regulator , microbiology and biotechnology , regulator , dnaa , phosphorylation , phagosome , intracellular , kinase , immunoprecipitation , gene , dna binding protein , biochemistry , transcription factor , mutant
Summary 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 dna A, 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 dna A promoter in vivo indicating that dna A promoter is a MtrA target. Simultaneous overexpression of mtr A regulator and its cognate mtr B kinase neither inhibited growth nor sharply increased the expression levels of dna A 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.