PknB kinase activity is regulated by phosphorylation in two Thr residues and dephosphorylation by PstP, the cognate phospho-Ser/Thr phosphatase, Mycobacterium tuberculosis

Unité de Biochimie Structurale, URA 2185 CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, cedex 15, France.
Molecular Microbiology (Impact Factor: 4.42). 10/2003; 49(6):1493-508. DOI: 10.1046/j.1365-2958.2003.03657.x
Source: PubMed


Bacterial genomics revealed the widespread presence of eukaryotic-like protein kinases and phosphatases in prokaryotes, but little is known on their biochemical properties, regulation mechanisms and physiological roles. Here we focus on the catalytic domains of two trans-membrane enzymes, the Ser/Thr protein kinase PknB and the protein phosphatase PstP from Mycobacterium tuberculosis. PstP was found to specifically dephosphorylate model phospho-Ser/Thr substrates in a Mn2+-dependent manner. Autophosphorylated PknB was shown to be a substrate for Pstp and its kinase activity was affected by PstP-mediated dephosphorylation. Two threonine residues in the PknB activation loop, found to be mostly disordered in the crystal structure of this kinase, namely Thr171 and Thr173, were identified as the target for PknB autophosphorylation and PstP dephosphorylation. Replacement of these threonine residues by alanine significantly decreased the kinase activity, confirming their direct regulatory role. These results indicate that, as for eukaryotic homologues, phosphorylation of the activation loop provides a regulation mechanism of mycobacterial kinases and strongly suggest that PknB and PstP could work as a functional pair in vivo to control mycobacterial cell growth.

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Available from: Frederique Pompeo, Nov 20, 2014
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    • "The M. tuberculosis genome also includes three genes (pstP, ptpA, and ptpB) encoding eukaryotic-like protein phosphatases in addition to STPKs. PstP is a metalloenzyme that belongs to the PPM family of Ser/Thr protein phosphatases, which is known to dephosphorylate various mycobacterial STPKs and their substrates (Boitel et al., 2003; Chopra et al., 2003; Durán et al., 2005). "
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    ABSTRACT: Tuberculosis continues to be a major cause of mortality worldwide despite significant advances in chemotherapy and development of the BCG vaccine. Although curable, the tuberculosis treatment period (6-9 months) presents many concerns, including patient noncompliance and the development of drug toxicity and drug resistance. This study aimed to understand the protein-protein interactions of key proteins involved in the Mycobacterium tuberculosis STPK signal transduction pathway (such as PknB, PknE, and PstP); in addition, we attempted to identify promising leads for the inhibition of protein-protein interactions. Interactome analyses revealed the interactions of these protein targets with several other proteins, including PknG and PbpA. Drug-like candidates were screened based on Lipinski's rule of five and the absorption digestion metabolism excretion toxicity. Molecular docking of the target proteins with the selected ligands identified cryptolepine HCl to be a common molecule interacting with all protein targets (with a good docking score). The generation of a pharmacophore model for cryptolepine HCl revealed three pharmacophoric regions: aromatic hydrocarbon, hydrogen bond acceptor, and hydrogen bond donor, which play important roles in its interaction with the protein targets. Therefore, cryptolepine HCl appears to be a promising drug candidate for further optimization and validation against M. tuberculosis.
    Full-text · Article · Sep 2015 · Genetics and molecular research: GMR
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    • "M. tuberculosis PKnB (EC - is a trans-membrane Ser/Thr protein kinase (STPK) highly conserved in Gram-positive bacteria and apparently essential for mycobacterial viability [3]. Earlier it was shown that PKnB is regulated by auto-phosphorylation an dephosphorylation by the Ser/Thr protein phosphatase [4] and [5] and recent work showed that PKnB is predominantly expressed during exponential growth, where as its over expression causes morphological changes linked to defects in cell wall synthesis and cell division [6]. Aberrant kinase activity is implicated in numerous human diseases and, not surprisingly, protein kinases represent today one of the most important groups of drug targets [7] and [8]. "
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    Full-text · Article · Jan 2014
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    • "There are few experimentally characterized phosphatases in M. tuberculosis. These include Rv3214 and Rv2419c, which are histidine phosphatases [3,17], PtpA and PtpB which are tyrosine protein phosphatases [41,42], and PstP, a serine/threonine protein phosphatases [43]. The specific substrates of these phosphatases have not been identified yet, with the exception of Rv2419c, a glucosyl-3-phosphoglycerate phosphatase [17]. "
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    Full-text · Article · Dec 2013 · BMC Microbiology
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