McEvoy M M, Hausrath A C, Randolph G B, Remington S J, Dahlquist F W
Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
Proc Natl Acad Sci U S A. 1998 Jun 23;95(13):7333-8. doi: 10.1073/pnas.95.13.7333.
The crystal structure at 2.0-A resolution of the complex of the Escherichia coli chemotaxis response regulator CheY and the phosphoacceptor-binding domain (P2) of the kinase CheA is presented. The binding interface involves the fourth and fifth helices and fifth beta-strand of CheY and both helices of P2. Surprisingly, the two heterodimers in the asymmetric unit have two different binding modes involving the same interface, suggesting some flexibility in the binding regions. Significant conformational changes have occurred in CheY compared with previously determined unbound structures. The active site of CheY is exposed by the binding of the kinase domain, possibly to enhance phosphotransfer from CheA to CheY. The conformational changes upon complex formation as well as the observation that there are two different binding modes suggest that the plasticity of CheY is an essential feature of response regulator function.
本文展示了大肠杆菌趋化反应调节因子CheY与激酶CheA的磷酸受体结合结构域（P2）复合物在2.0埃分辨率下的晶体结构。结合界面涉及CheY的第四和第五螺旋以及第五β链和P2的两个螺旋。令人惊讶的是，不对称单元中的两个异二聚体具有涉及相同界面的两种不同结合模式，这表明结合区域存在一定的灵活性。与先前确定的未结合结构相比，CheY发生了显著的构象变化。激酶结构域的结合使CheY的活性位点暴露，这可能增强了磷酸从CheA转移到CheY的过程。复合物形成时的构象变化以及存在两种不同结合模式的观察结果表明，CheY的可塑性是反应调节因子功能的一个基本特征。
