Mycobacterium tuberculosis PknK Substrate Profiling Reveals Essential Transcription Terminator Protein Rho and Two-Component Response Regulators PrrA and MtrA as Novel Targets for Phosphorylation

Abstract

Networks of gene regulation and signaling cascades are fundamental to the pathogenesis of Mycobacterium tuberculosis in adapting to the continuously changing intracellular environment in the host. M. tuberculosis protein kinase K is a transcription regulator that responds to diverse environmental signals and facilitates stress-induced growth adaptation in culture and during infection. This study identifies multiple signaling interactions of PknK and provides evidence that PknK can change the transcriptional landscape during growth transitions by connecting distinctly different signal transduction and regulatory pathways essential for mycobacterial survival.

Anti-cancer drug Tamoxifen interferes withMycobacterium tuberculosisPhoPR mediated signaling and inhibits mycobacterial growth

“…S2). Recent studies have revealed the involvement of M. tb PknK in regulating PrrA and MtrA RRs, which are essential for mycobacterial growth and survival (11, 12, 32). However, very little is known about the O -phosphorylation of HKs through the Ser/Thr protein kinases.…”

“…We also show STPK-mediated phosphorylation of a mycobacterial histidine kinase. PhoR is subjected to O-phosphorylation by M. tb Ser/Thr Protein kinase K (PknK), a soluble / membrane-associated kinase, that has multiple TCS RRs as targets (32).…”

“…The traditional belief that TCS signaling pathways are linear has now been replaced with concrete evidence from several studies showing extensive cross-talk between cognate and non-cognate pairs of SKs and RRs (29, 30). Furthermore, the emerging network is no longer restrictive to TCS components but extends to M. tb STPKs as well (8, 31, 32). Conceivably, these added layers of regulation allow fine tuning of regulatory pathways critical for pathogenesis and intracellular survival.…”

Ser/Thr Phosphorylation ofMycobacterium tuberculosisType II Rel TA module by Protein Kinase K interferes with toxin neutralization: A novel mode of TA regulation

“…We establish Ser/Thr phosphorylation of the toxin component as means to disrupt TA complex formation, rendering the toxin to inhibit growth and initiate persistence. The upregulation of rel and pknK transcripts under conditions of nitrogen starvation (34, 35) suggests that these cellular environments may be where PknK-mediated phosphorylation of Rel proteins is most physiologically relevant. We predict that other STPKs may similarly act to modify the TA proteins under different activating environments.…”

“…All three loci have been characterized as bona fide TA modules (19) that are responsive to stress environments such as nitrogen starvation and inhibit growth by targeting translation (34). We explored a link between the Rel TA modules and PknK, a cytosolic Ser/Thr Protein Kinase (STPK) that is coincidentally also induced under nitrogen starvation (35), and is implicated in translational control mechanisms (36). We demonstrate that PknK interacts with the RelE toxin and RelJK TA proteins in vivo .…”