Nguyen Hien-Anh, El Khoury Takla, Guiral Sébastien, Laaberki Maria-Halima, Candusso Marie-Pierre, Galisson Frédéric, Foucher Anne-Emmanuelle, Kesraoui Salsabil, Ballut Lionel, Vallet Sylvain, Orelle Cédric, Zucchini Laure, Martin Juliette, Page Adeline, Attieh Jihad, Aghajari Nushin, Grangeasse Christophe, Jault Jean-Michel
Institut de Biologie Structurale, Université Joseph Fourier Grenoble 1, UMR5075 CNRS/CEA/UJF, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1, France.
Institut de Biologie Structurale, Université Joseph Fourier Grenoble 1, UMR5075 CNRS/CEA/UJF, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1, France; University of Lyon, CNRS, UMR5086 "Molecular Microbiology and Structural Biochemistry," 7 Passage du Vercors, F-69367 Lyon, France; Department of Biology, Faculty of Sciences, University of Balamand, Lebanon.
J Mol Biol. 2017 Oct 13;429(20):3056-3074. doi: 10.1016/j.jmb.2017.08.016. Epub 2017 Sep 7.
Fine tuning of signaling pathways is essential for cells to cope with sudden environmental variations. This delicate balance is maintained in particular by protein kinases that control the activity of target proteins by reversible phosphorylation. In addition to homologous eukaryotic enzymes, bacteria have evolved some specific Ser/Thr/Tyr protein kinases without any structural resemblance to their eukaryotic counterparts. Here, we show that a previously identified family of ATPases, broadly conserved among bacteria, is in fact a new family of protein kinases with a Ser/Thr/Tyr kinase activity. A prototypic member of this family, YdiB from Bacillus subtilis, is able to autophosphorylate and to phosphorylate a surrogate substrate, the myelin basic protein. Two crystal structures of YdiB were solved (1.8 and 2.0Å) that display a unique ATP-binding fold unrelated to known protein kinases, although a conserved HxD motif is reminiscent of that found in Hanks-type protein kinases. The effect of mutations of conserved residues further highlights the unique nature of this new protein kinase family that we name ubiquitous bacterial kinase. We investigated the cellular role of YdiB and showed that a ∆ydiB mutant was more sensitive to paraquat treatment than the wild type, with ~13% of cells with an aberrant morphology. In addition, YdiE, which is known to participate with both YdiC and YdiB in an essential chemical modification of some specific tRNAs, is phosphorylated in vitro by YdiB. These results expand the boundaries of the bacterial kinome and support the involvement of YdiB in protein translation and resistance to oxidative stress in B. subtilis.
信号通路的精细调节对于细胞应对突然的环境变化至关重要。这种微妙的平衡尤其通过蛋白激酶来维持，蛋白激酶通过可逆磷酸化作用控制靶蛋白的活性。除了同源的真核酶外，细菌还进化出了一些特定的丝氨酸/苏氨酸/酪氨酸蛋白激酶，它们与真核对应物没有任何结构相似性。在这里，我们表明，先前在细菌中广泛保守的一个ATP酶家族实际上是一个具有丝氨酸/苏氨酸/酪氨酸激酶活性的新蛋白激酶家族。该家族的一个原型成员，来自枯草芽孢杆菌的YdiB，能够自磷酸化并磷酸化替代底物髓鞘碱性蛋白。解析了YdiB的两个晶体结构（1.8 Å和2.0 Å），它们显示出与已知蛋白激酶无关的独特ATP结合折叠，尽管保守的HxD基序让人联想到在汉克斯型蛋白激酶中发现的基序。保守残基突变的影响进一步突出了这个我们命名为普遍存在的细菌激酶的新蛋白激酶家族的独特性质。我们研究了YdiB的细胞作用，结果表明，与野生型相比，∆ydiB突变体对百草枯处理更敏感，约13%的细胞形态异常。此外，已知与YdiC和YdiB共同参与某些特定tRNA的重要化学修饰的YdiE，在体外被YdiB磷酸化。这些结果扩展了细菌激酶组的范围，并支持YdiB参与枯草芽孢杆菌的蛋白质翻译和对氧化应激的抗性。
