J Biol Chem. 2014 Jul 25;289(30):20422-33. doi: 10.1074/jbc.M114.559054.
Many Gram-positive bacteria coordinate cellular processes by signaling through Ser/Thr protein kinases (STPKs), but the architecture of these phosphosignaling cascades is unknown. To investigate the network structure of a prokaryotic STPK system, we comprehensively explored the pattern of signal transduction in the Mycobacterium tuberculosis Ser/Thr kinome. Autophosphorylation is the dominant mode of STPK activation, but the 11 M. tuberculosis STPKs also show a specific pattern of efficient cross-phosphorylation in vitro. The biochemical specificity intrinsic to each kinase domain was used to map the provisional signaling network, revealing a three-layer architecture that includes master regulators, signal transducers, and terminal substrates. Fluorescence microscopy revealed that the STPKs are specifically localized in the cell. Master STPKs are concentrated at the same subcellular sites as their substrates, providing additional support for the biochemically defined network. Together, these studies imply a branched functional architecture of the M. tuberculosis Ser/Thr kinome that could enable horizontal signal spreading. This systems-level approach provides a biochemical and spatial framework for understanding Ser/Thr phospho-signaling in M. tuberculosis, which differs fundamentally from previously defined linear histidine kinase cascades.
许多革兰氏阳性菌通过 Ser/Thr 蛋白激酶（STPK）进行信号传递来协调细胞过程，但这些磷酸信号级联的结构尚不清楚。为了研究原核 STPK 系统的网络结构，我们全面探索了结核分枝杆菌 Ser/Thr 激酶组中的信号转导模式。自身磷酸化是 STPK 激活的主要模式，但 11 种结核分枝杆菌 STPK 也表现出体外有效交叉磷酸化的特定模式。每个激酶结构域固有的生化特异性用于绘制暂定信号网络，揭示了包括主调控因子、信号转导因子和末端底物的三层结构。荧光显微镜显示 STPK 特异性定位于细胞中。主 STPK 与它们的底物集中在相同的亚细胞部位，为生化定义的网络提供了额外的支持。总之，这些研究表明结核分枝杆菌 Ser/Thr 激酶组具有分支功能结构，可实现水平信号传播。这种系统水平的方法为理解结核分枝杆菌中的 Ser/Thr 磷酸信号提供了生化和空间框架，这与以前定义的线性组氨酸激酶级联有根本区别。
