Inserm Equipe Avenir Biology of Intracellular Pathogens, Institut Pasteur Korea, Seoul, Republic of Korea.
Unit of Mycobacterial Genetics, Institut Pasteur, Paris, France.
Microbiology (Reading). 2010 Jun;156(Pt 6):1619-1631. doi: 10.1099/mic.0.038133-0. Epub 2010 Feb 25.
Eukaryotic-like Ser/Thr protein kinases (STPKs) are present in many bacterial species, where they control various physiological and virulence processes by enabling microbial adaptation to specific environmental signals. PknJ is the only member of the 11 STPKs identified in Mycobacterium tuberculosis that still awaits characterization. Here we report that PknJ is a functional kinase that forms dimers in vitro, and contains a single transmembrane domain. Using a high-density peptide-chip-based technology, multiple potential mycobacterial targets were identified for PknJ. We confirmed PknJ-dependent phosphorylation of four of these targets: PknJ itself, which autophosphorylates at Thr(168), Thr(171) and Thr(173) residues; the transcriptional regulator EmbR; the methyltransferase MmaA4/Hma involved in mycolic acid biosynthesis; and the dipeptidase PepE, whose encoding gene is located next to pknJ in the mycobacterial genome. Our results provide a number of candidate phospho-targets for PknJ and possibly other mycobacterial STPKs that could be studied to investigate the role of STPKs in M. tuberculosis physiology and virulence.
真核样丝氨酸/苏氨酸蛋白激酶（STPK）存在于许多细菌物种中，通过使微生物适应特定的环境信号，它们控制着各种生理和毒力过程。在结核分枝杆菌中鉴定出的 11 种 STPK 中，只有 PknJ 仍然有待表征。在这里，我们报告说 PknJ 是一种功能性激酶，它在体外形成二聚体，并包含一个单一的跨膜结构域。使用高密度肽芯片技术，为 PknJ 鉴定了多个潜在的分枝杆菌靶标。我们证实了 PknJ 对其中四个靶标的依赖性磷酸化：自身磷酸化 Thr(168)、Thr(171)和 Thr(173)残基的 PknJ 本身；转录调节剂 EmbR；参与分枝菌酸生物合成的甲基转移酶 MmaA4/Hma；以及二肽酶 PepE，其编码基因位于分枝杆菌基因组中 pknJ 的旁边。我们的结果为 PknJ 和其他可能的分枝杆菌 STPK 的许多候选磷酸化靶标提供了依据，这些靶标可以进一步研究以调查 STPK 在结核分枝杆菌生理和毒力中的作用。
