University of Würzburg, Institute for Molecular Infection Biology, Würzburg, Germany.
University of Tübingen, IMIT - Infection biology, Tübingen, Germany.
Sci Rep. 2018 Sep 12;8(1):13693. doi: 10.1038/s41598-018-32109-7.
The cell wall synthesis pathway producing peptidoglycan is a highly coordinated and tightly regulated process. Although the major components of bacterial cell walls have been known for decades, the complex regulatory network controlling peptidoglycan synthesis and many details of the cell division machinery are not well understood. The eukaryotic-like serine/threonine kinase Stk and the cognate phosphatase Stp play an important role in cell wall biosynthesis and drug resistance in S. aureus. We show that stp deletion has a pronounced impact on cell wall synthesis. Deletion of stp leads to a thicker cell wall and decreases susceptibility to lysostaphin. Stationary phase Δstp cells accumulate peptidoglycan precursors and incorporate higher amounts of incomplete muropeptides with non-glycine, monoglycine and monoalanine interpeptide bridges into the cell wall. In line with this cell wall phenotype, we demonstrate that the lipid II:glycine glycyltransferase FemX can be phosphorylated by the Ser/Thr kinase Stk in vitro. Mass spectrometric analyses identify Thr32, Thr36 and Ser415 as phosphoacceptors. The cognate phosphatase Stp dephosphorylates these phosphorylation sites. Moreover, Stk interacts with FemA and FemB, but is unable to phosphorylate them. Our data indicate that Stk and Stp modulate cell wall synthesis and cell division at several levels.
细胞壁合成途径产生肽聚糖是一个高度协调和严格调控的过程。尽管细菌细胞壁的主要成分已经为人所知数十年，但控制肽聚糖合成的复杂调控网络以及细胞分裂机制的许多细节仍未得到很好的理解。真核样丝氨酸/苏氨酸激酶 Stk 和同源磷酸酶 Stp 在金黄色葡萄球菌的细胞壁生物合成和耐药性中发挥重要作用。我们表明，stp 缺失对细胞壁合成有明显影响。stp 的缺失导致细胞壁变厚，并降低对溶菌酶的敏感性。静止期Δstp 细胞积累肽聚糖前体，并将更多数量的非甘氨酸、单甘氨酸和单丙氨酸间肽桥的不完整 muropeptides 掺入细胞壁。与这种细胞壁表型一致，我们证明脂质 II:甘氨酸糖基转移酶 FemX 可以在体外被丝氨酸/苏氨酸激酶 Stk 磷酸化。质谱分析鉴定 Thr32、Thr36 和 Ser415 为磷酸受体。同源磷酸酶 Stp 去磷酸化这些磷酸化位点。此外，Stk 与 FemA 和 FemB 相互作用，但不能磷酸化它们。我们的数据表明，Stk 和 Stp 在多个层面上调节细胞壁合成和细胞分裂。
