Structure of the full-length HPr kinase/phosphatase from Staphylococcus xylosus at 1.95 Å resolution:: Mimicking the product/substrate of the phospho transfer reactions
Structure of the full-length HPr kinase/phosphatase from Staphylococcus xylosus at 1.95 Å resolution:: Mimicking the product/substrate of the phospho transfer reactions
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DOI：
10.1073/pnas.052461499
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发表时间：
2002-03-19
影响因子：
11.1
通讯作者：
Scheffzek, K
中科院分区：
文献类型：
--
作者：
Márquez, JA;Hasenbein, S;Scheffzek, K
含组氨酸的磷酸载体蛋白 (HPr) 激酶/磷酸酶参与碳分解代谢物抑制，主要在革兰氏阳性细菌中。它是一种双功能酶，可在 ATP 依赖性反应中磷酸化 Ser-46-HPr，并使 P-Ser-46-HPr 去磷酸化。对木糖葡萄球菌全长结晶酶的 X 射线分析（分辨率为 1.95 埃）显示，该酶由两个清晰分离的结构域组成，这两个结构域组装成类似于三叶螺旋桨的六聚体结构。 N 末端结构域具有与糖磷酸转移酶系统的酶 I 的片段以及 MurF 的尿苷结合部分类似的 βαβ 折叠；它在结构上由三个二聚体模块组成，暴露形成螺旋桨叶片。在 N 端二聚体界面中发现了两个与高度保守残基相关的意想不到的磷酸根离子。 C 端激酶结构域与干酪乳杆菌酶的 C 端激酶结构域相似，以六个拷贝组装形成螺旋桨的紧凑中心轮毂。除了之前报道的与腺苷酸激酶的相似性之外，我们还提出了与磷酸烯醇丙酮酸羧激酶的进化关系。除了激酶结构域磷酸盐结合环中的磷酸盐离子外，我们还确定了第二个磷酸盐结合位点，与腺苷酸激酶相比，我们认为该位点可容纳产物/底物磷酸盐，通常与 HPr 的 Ser-46 共价连接。因此，我们建议我们的结构代表激酶/磷酸酶反应的产物/底物模拟。
The histidine containing phospho carrier protein (HPr) kinase/phosphatase is involved in carbon catabolite repression, mainly in Grampositive bacteria. It is a bifunctional enzyme that phosphorylates Ser-46-HPr in an ATP-dependent reaction and dephosphorylates P-Ser-46-HPr. X-ray analysis of the full-length crystalline enzyme from Staphylococcus xylosus at a resolution of 1.95 Angstrom shows the enzyme to consist of two clearly separated domains that are assembled in a hexameric structure resembling a three-bladed propeller. The N-terminal domain has a betaalphabeta fold similar to a segment from enzyme I of the sugar phospho transferase system and to the uridyl-binding portion of MurF; it is structurally organized in three dimeric modules exposed to form the propeller blades. Two unexpected phosphate ions associated with highly conserved residues were found in the N-terminal dimeric interface. The C-terminal kinase domain is similar to that of the Lactobacillus casei enzyme and is assembled in six copies to form the compact central hub of the propeller. Beyond previously reported similarity with adenylate kinase, we suggest evolutionary relationship with phosphoenolpyruvate carboxykinase. in addition to a phosphate ion in the phosphate-binding loop of the kinase domain, we have identified a second phosphate-binding site that, by comparison with adenylate kinases, we believe accommodates a product/substrate phosphate, normally covalently linked to Ser-46 of HPr. Thus, we propose that our structure represents a product/substrate mimic of the kinase/phosphatase reaction.