Mycobacterium tuberculosis protein kinase K enables growth adaptation through translation control.
Mycobacterium tuberculosis serine/threonine protein kinases (STPKs) are responsible for orchestrating critical metabolic and physiological changes that dictate mycobacterial growth adaptation. Previously, we established that PknK participates in regulatory pathways that slow the growth of M. tuberculosis in a variety of in vitro stress environments and during persistent infection in mice. In the present study, we have elaborated on the mechanism of PknK-mediated regulation. Through transcription profiling of wild-type H37Rv and a ΔpknK mutant strain during logarithmic and stationary growth phases, we determined that PknK regulates the expression of a large subset of tRNA genes so that regulation is synchronized with growth phase and cellular energy status. Elevated levels of wild-type M. tuberculosis PknK (PknK(Mtb)), but not phosphorylation-defective PknK(Mtb), in Mycobacterium smegmatis cause significant retardation of the growth rate and altered colony morphology. We investigated a role for PknK in translational control and established that PknK directs the inhibition of in vitro transcription and translation processes in a phosphorylation-dependent manner. Increasing concentrations of ATP or PknK exert cooperative effects and enhance the inhibitory function of PknK. Furthermore, truncation and mutational analyses of PknK revealed that PknK is autoregulated via intramolecular interactions with its C-terminal region. Significantly, the invariant lysine 55 residue was only essential for activity in the full-length PknK protein, and the truncated mutant proteins were active. A model for PknK autoregulation is proposed and discussed.
Center for Infectious Diseases and Vaccinology, Biodesign Institute, Arizona State University, Tempe, Arizona, USA. vandana.malhotra@asu.edu
Vandana
V
Malhotra
Blessing P
BP
Okon
Josephine E
JE
Clark-Curtiss
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D020102:Mycobacterium smegmatis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000096:biosynthesis
D001426:Bacterial Proteins; D012343:RNA, Transfer; C554363:Pknk protein, Mycobacterium tuberculosis; D017346:Protein Serine-Threonine Kinases