PknB kinase activity is regulated by phosphorylation in two Thr residues and dephosphorylation by PstP, the cognate phospho-Ser/Thr phosphatase, in Mycobacterium tuberculosis
PknB kinase activity is regulated by phosphorylation in two Thr residues and dephosphorylation by PstP, the cognate phospho-Ser/Thr phosphatase, in Mycobacterium tuberculosis
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DOI：
10.1046/j.1365-2958.2003.03657.x
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发表时间：
2003-09-01
影响因子：
3.6
通讯作者：
Alzari, PM
中科院分区：
文献类型：
--
作者：
Boitel, B;Ortiz-Lombardía, M;Alzari, PM
细菌基因组学揭示了真核样蛋白激酶和磷酸酶在原核生物中的广泛存在，但在其生化特性，调节机制和生理作用方面鲜为人知。在这里，我们关注两种反式膜酶的催化结构域，Ser/ Thr蛋白激酶PKNB和来自结核分枝杆菌的蛋白质磷酸酶PSTP。发现PSTP以MN2+依赖性方式特异性地磷酸化模型磷酸化模型/THR底物。自磷酸化的PKNB被证明是PSTP的底物，其激酶活性受PSTP介导的去磷酸化的影响。 PKNB激活环中的两个苏氨酸残基被认为在该激酶的晶体结构中大多无序，即THR171和THR173，被鉴定为PKNB自磷酸化和PSTP Dephosphoration的靶标。丙氨酸替代这些苏氨酸残基可显着降低激酶活性，从而确认其直接调节作用。这些结果表明，至于真核同源物，激活环的磷酸化提供了分枝杆菌激酶的调节机制，并强烈表明PKNB和PSTP可以在体内作为功能对来控制分枝杆菌细胞的生长。
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.