Pyrophosphate-producing protein dephosphorylation by HPr kinase/phosphorylase: A relic of early life?
Pyrophosphate-producing protein dephosphorylation by HPr kinase/phosphorylase: A relic of early life?
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DOI：
10.1073/pnas.212410399
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发表时间：
2002-10-15
影响因子：
11.1
通讯作者：
Deutscher, J
中科院分区：
文献类型：
--
作者：
Mijakovic, I;Poncet, S;Deutscher, J
在大多数革兰氏阳性细菌中，丝氨酸 46 磷酸化 HPr (P-Ser-HPr) 通过充当分解代谢辅阻遏物来控制众多分解代谢基因（约占其基因组的 10%）的表达。 HPr 激酶/磷酸化酶 (HprK/P) 是一种用于抑制分解代谢物的双功能传感器酶，在 ATIP 和 1,6-二磷酸果糖存在的情况下，使 HPr（糖转运磷酸烯醇丙酮酸/糖磷酸转移酶系统的磷酸载体蛋白）磷酸化，但在存在 ATIP 和 1,6-二磷酸果糖的情况下，使 P-Ser-HPr 去磷酸化 磷酸盐优于 ATP 和 1,6-二磷酸果糖。我们在此证明 P-Ser-HPr 去磷酸化会导致 HPr 和焦磷酸盐的形成。 HPrK/P 与 ATP 的 β 磷酸盐结合在同一位点，可能利用无机磷酸盐对 P-Ser-HPr 中的磷酰基键进行亲核攻击。 HPrK/P 是已知的第一种通过这种磷酸磷酸解机制催化 P 蛋白去磷酸化的酶。该反应是可逆的，并且在焦磷酸浓度升高时，HprK/P 可以利用焦磷酸使 HPr 磷酸化。枯草芽孢杆菌在葡萄糖上的生长将细胞内焦磷酸盐浓度增加到（大约 6 mM），这在体外测试中允许有效的焦磷酸盐依赖性 HPr 磷酸化。为了在葡萄糖耗尽时有效地使 P-Ser-HPr 去磷酸化，细胞中的焦磷酸盐浓度降低至 1 mM。在枯草芽孢杆菌中，这可能是通过 YvoE 实现的。该蛋白具有焦磷酸酶活性，其基因与 hprK 一起组织在操纵子中。
In most Gram-positive bacteria, serine-46-phosphorylated HPr (P-Ser-HPr) controls the expression of numerous catabolic genes (approximate to10% of their genome) by acting as catabolite corepressor. HPr kinase/phosphorylase (HprK/P), the bifunctional sensor enzyme for catabolite repression, phosphorylates HPr, a phosphocarrier protein of the sugar-transporting phosphoenolpyruvate/glycose phosphotransferase system, in the presence of ATIP and fructose-1,6-bisphosphate but dephosphorylates P-Ser-HPr when phosphate prevails over ATP and fructose-1,6-bisphosphate. We demonstrate here that P-Ser-HPr dephosphorylation leads to the formation of HPr and pyrophosphate. HprK/P, which binds phosphate at the same site as the beta phosphate of ATP, probably uses the inorganic phosphate to carry out a nucleophilic attack on the phosphoryl bond in P-Ser-HPr. HprK/P is the first enzyme known to catalyze P-protein dephosphorylation via this phosphophosphorolysis mechanism. This reaction is reversible, and at elevated pyrophosphate concentrations, HprK/P can use pyrophosphate to phosphorylate HPr. Growth of Bacillus subtilis on glucose increased intracellular pyrophosphate to concentrations (approximate to6 mM), which in in vitro tests allowed efficient pyrophosphate-dependent HPr phosphorylation. To effectively dephosphorylate P-Ser-HPr when glucose is exhausted, the pyrophosphate concentration in the cells is lowered to 1 mM. In B. subtilis, this might be achieved by YvoE. This protein exhibits pyrophosphatase activity, and its gene is organized in an operon with hprK.