Serine phosphorylation regulates the P-type potassium pump KdpFABC.
Serine phosphorylation regulates the P-type potassium pump KdpFABC.
复制标题
DOI：
10.7554/elife.55480
复制
发表时间：
2020-09-21
期刊：
影响因子：
7.7
通讯作者：
Stokes DL
中科院分区：
文献类型：
--
作者：
Sweet ME;Zhang X;Erdjument-Bromage H;Dubey V;Khandelia H;Neubert TA;Pedersen BP;Stokes DL
KdpFABC是一种ATP依赖性K+泵，可确保细菌在K+缺乏的环境中存活。尽管kdpFABC表达的转录激活已被充分研究，但尚未描述当K+水平恢复时下调的机制。在这里，我们表明，KdpFABC被抑制时，细胞返回到K+丰富的环境。抑制机制涉及KdpB上Ser 162的磷酸化，其可以通过用丝氨酸磷酸酶处理在体外逆转。将Ser 162突变为丙氨酸产生组成型活性，而拟磷酸化Ser 162 Asp突变使泵失活。对转运循环的分析表明，丝氨酸磷酸化消除了ATP水解的K+依赖性，并在形成磷酸戊二酯中间体（E1~P）后阻断了催化循环。这种调节机制在P型泵中是独特的，这项研究进一步加深了我们对细菌如何控制钾稳态以维持细胞体积和渗透势的理解。
KdpFABC is an ATP-dependent K+ pump that ensures bacterial survival in K+-deficient environments. Whereas transcriptional activation of kdpFABC expression is well studied, a mechanism for down-regulation when K+ levels are restored has not been described. Here, we show that KdpFABC is inhibited when cells return to a K+-rich environment. The mechanism of inhibition involves phosphorylation of Ser162 on KdpB, which can be reversed in vitro by treatment with serine phosphatase. Mutating Ser162 to Alanine produces constitutive activity, whereas the phosphomimetic Ser162Asp mutation inactivates the pump. Analyses of the transport cycle show that serine phosphorylation abolishes the K+-dependence of ATP hydrolysis and blocks the catalytic cycle after formation of the aspartyl phosphate intermediate (E1~P). This regulatory mechanism is unique amongst P-type pumps and this study furthers our understanding of how bacteria control potassium homeostasis to maintain cell volume and osmotic potential.