Crystal structures of the signal transducing protein G1nK from Thermus thermophilus HB8
Crystal structures of the signal transducing protein G1nK from Thermus thermophilus HB8
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DOI：
10.1016/j.jsb.2004.08.007
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发表时间：
2005-01-01
影响因子：
3
通讯作者：
Yokoyama, S
中科院分区：
文献类型：
--
作者：
Sakai, H;Wang, HF;Yokoyama, S
嗜热热菌HB8基因组编码PII信号转导蛋白GlnK。在两个不同的空间群P2(1)2(1)2(1)和P3(1)21中确定了GlnK的晶体结构。PII蛋白具有t环，这是与受体蛋白相互作用所必需的。在这两种晶体形式中，三个GlnK分子在不对称单元中形成三聚体。在一种P2(1)2(1)2(1)晶体形式中，三聚体中的三个t环是无序的，而在另一种P2(1)2(1)2(1)晶体形式中，三聚体中一个分子的t环是有序的。在P3(1)21晶体中，一个t环是有序的，而另外两个t环是无序的。有序t型环的构象在两种晶体形式之间有显著差异：一种是在t型环的中间形成α -螺旋。而另一个则是β发夹的延伸。晶体触点捕获了两种不同的构象。对多个t -环构象的观察表明，t -环可能表现出“多聚性”，这对与受体蛋白的相互作用很重要。核苷酸结合形式的晶体结构。GlnK(。)ATP和GlnKADP，也已确定。在两个相邻的嗜热t菌GlnK单体的界面间隙内ATP/ADP结合可能会影响t环的构象。(C) 2004爱思唯尔公司版权所有。
The Thermus thermophilus HB8 genome encodes a signal transducing PII protein, GlnK. The crystal structures of GlnK have been determined in two different space groups, P2(1)2(1)2(1) and P3(1)21. The PII protein has the T-loop, which is essential for interactions with receptor proteins. In both crystal forms, three GlnK molecules form a trimer in the asymmetric unit. In one P2(1)2(1)2(1) crystal form, the three T-loops in the trimer are disordered, while in another P2(1)2(1)2(1) crystal form, the T-loop from one molecule in the trimer is ordered. In the P3(1)21 crystal, one T-loop is ordered while the other two T-loops are disordered. The conformations of the ordered T-loops significantly differ between the two crystal forms: one makes the alpha-helix in the middle of the T-loop. while the other has an extension of the beta-hairpin. Two different conformations are captured by the crystal contacts. The observation of multiple T-loop conformations suggests that the T-loop could potentially exhibit "polysterism," which would be important for interactions with receptor proteins. The crystal structures of the nucleotide-bound forms. GlnK(.)ATP and GlnK(.)ADP, have also been determined. ATP/ADP binding within a cleft at the interface of two adjacent T. thermophilus GlnK monomers might affect the conformation of the T-loop. (C) 2004 Elsevier Inc. All rights reserved.