Muench Stephen P, Xu Ling, Sedelnikova Svetlana E, Rice David W
Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
Proc Natl Acad Sci U S A. 2006 Aug 15;103(33):12359-64. doi: 10.1073/pnas.0602585103. Epub 2006 Aug 7.
The structure of a Bacillus subtilis YphC/GDP complex shows that it contains two GTPase domains that pack against a central domain whose fold resembles that of an RNA binding KH-domain. Comparisons of this structure to that of a homologue in Thermotoga maritima reveals a dramatic rearrangement in the position of the N-terminal GTPase domain with a shift of up to 60 A and the formation of a totally different interface to the central domain. This rearrangement appears to be triggered by conformational changes of the switch II region in this domain in response to nucleotide binding. Modeling studies suggest that this motion represents transitions between the "on" and "off" states of the GTPase, the effect of which is to alternately expose and bury a positively charged face of the central domain that we suggest is involved in RNA recognition as part of the possible role of this enzyme in ribosome binding.
枯草芽孢杆菌YphC/GDP复合物的结构表明,它包含两个GTPase结构域,这两个结构域与一个中央结构域紧密堆积,该中央结构域的折叠类似于RNA结合KH结构域。将该结构与海栖热袍菌中的同源物结构进行比较,发现N端GTPase结构域的位置发生了显著重排,移动距离达60埃,并且与中央结构域形成了完全不同的界面。这种重排似乎是由该结构域中开关II区域响应核苷酸结合而发生的构象变化触发的。建模研究表明,这种运动代表了GTPase“开”和“关”状态之间的转变,其作用是交替暴露和掩埋中央结构域带正电的表面,我们认为该表面参与RNA识别,这是该酶在核糖体结合中可能发挥的作用的一部分。