DevS/DosS sensor is bifunctional and its phosphatase activity precludes aerobic DevR/DosR regulon expression in Mycobacterium tuberculosis.
Two-component systems, comprising histidine kinases and response regulators, empower bacteria to sense and adapt to diverse environmental stresses. Some histidine kinases are bifunctional; their phosphorylation (kinase) and dephosphorylation (phosphatase) activities toward their cognate response regulators permit the rapid reversal of genetic responses to an environmental stimulus. DevR-DevS/DosR-DosS is one of the best-characterized two-component systems of Mycobacterium tuberculosis. The kinase function of DevS is activated by gaseous stress signals, including hypoxia, resulting in the induction of ~ 48-genes DevR dormancy regulon. Regulon expression is tightly controlled and lack of expression in aerobic Mtb cultures is ascribed to the absence of phosphorylated DevR. Here we show that DevS is a bifunctional sensor and possesses a robust phosphatase activity toward DevR. We used site-specific mutagenesis to generate substitutions in conserved residues in the dimerization and histidine phosphotransfer domain of DevS and determined their role in kinase/phosphatase functions. In vitro and in vivo experiments, including a novel in vivo phosphatase assay, collectively establish that these conserved residues are critical for regulating kinase/phosphatase functions. Our findings establish DevS phosphatase function as an effective control mechanism to block aerobic expression of the DevR dormancy regulon. Asp-396 is essential for both kinase and phosphatase functions, whereas Gln-400 is critical for phosphatase function. The positive and negative functions perform opposing roles in DevS: the kinase function triggers regulon induction under hypoxia, whereas its phosphatase function prevents expression under aerobic conditions. A finely tuned balance in these opposing activities calibrates the dormancy regulon response output.
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Kohinoor
K
Kaur
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Priyanka
P
Kumari
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Saurabh
S
Sharma
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Snigdha
S
Sehgal
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Jaya Sivaswami
JS
Tyagi
D000332:Aerobiosis; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006656:Protamine Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D000072417:Protein Domains; D011494:Protein Kinases / Q000378:metabolism*; D018085:Regulon
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C542863:DosR protein, Mycobacterium tuberculosis; D004247:DNA; D011494:Protein Kinases; C506260:DevS protein, Mycobacterium tuberculosis; D006656:Protamine Kinase; D010749:Phosphoprotein Phosphatases
DevR/DosR; DevS/DosS; Mycobacterium tuberculosis; dormancy regulon; histidine kinase; phosphatase