Th structure of the PII-ATP complex
Th structure of the PII-ATP complex
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DOI：
10.1046/j.1432-1327.2001.02074.x
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发表时间：
2001-04-01
期刊：
影响因子：
--
通讯作者：
Ollis, DL
中科院分区：
文献类型：
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作者：
Xu, YB;Carr, PD;Ollis, DL
P-II是一种信号转导蛋白，是许多细菌用来调节谷氨酰胺合成酶活性及其基因转录的细胞机制的一部分。使用六方晶型（晶型I）解析P-II的结构。P-II的更生理相关的形式是具有小分子效应物的复合物。我们描述了通过分析通过P-II与ATP共结晶获得的两种不同的晶型（II型和III型）获得的具有ATP的P-II的结构。两种结构都有一个无序的识别（T）环，并在其C末端显示出差异。这些结构与I型蛋白质的比较揭示了结合ATP时发生的变化。令人惊讶的是，P-II/ATP复合物的结构与功能同源物GlnK的结构不同。这两种蛋白质以类似的方式结合ATP的碱基和糖，但在与磷酸盐相互作用的方式上表现出差异。结构上的差异可以解释它们活性上的差异，这些差异归因于位置82处的序列差异。最近已经证明，P-II和GlnK在体内形成功能性异源三聚体。我们构建异源三聚体的模型，并检查亚基之间的连接。
P-II is a signal transduction protein that is part of the cellular machinery used by many bacteria to regulate the activity of glutamine synthetase and the transcription of its gene. The structure of P-II was solved using a hexagonal crystal form (form I). The more physiologically relevant form of P-II is a complex with small molecule effecters. We describe the structure of P-II with ATP obtained by analysis of two different crystal forms (forms II and III) that were obtained by co-crystallization of P-II with ATP. Both structures have a disordered recognition (T) loop and show differences at their C termini. Comparison of these structures with the form I protein reveals changes that occur on binding ATP. Surprisingly, the structure of the P-II/ATP complex differs with that of GlnK, a functional homologue. The two proteins bind the base and sugar of ATP in a similar manner but show differences in the way that they interact with the phosphates. The differences in structure could account for the differences in their activities, and these have been attributed to a difference in sequence at position 82. It has been demonstrated recently that P-II and GlnK form functional heterotrimers in vivo. We construct models of the heterotrimers and examine the junction between the subunits.