Gotthardt Katja, Weyand Michael, Kortholt Arjan, Van Haastert Peter J M, Wittinghofer Alfred
Department of Structural Biology, Max-Planck-Institut for Molecular Physiology, Dortmund, Germany.
EMBO J. 2008 Aug 20;27(16):2239-49. doi: 10.1038/emboj.2008.150. Epub 2008 Jul 24.
Ras of complex proteins (Roc) belongs to the superfamily of Ras-related small G-proteins that always occurs in tandem with the C-terminal of Roc (COR) domain. This Roc-COR tandem is found in the bacterial and eukaryotic world. Its most prominent member is the leucine-rich repeat kinase LRRK2, which is mutated and activated in Parkinson patients. Here, we investigated biochemically and structurally the Roco protein from Chlorobium tepidum. We show that Roc is highly homologous to Ras, whereas the COR domain is a dimerisation device. The juxtaposition of the G-domains and mutational analysis suggest that the Roc GTPase reaction is stimulated and/or regulated by dimerisation in a nucleotide-dependent manner. The region most conserved between bacteria and man is the interface between Roc and COR, where single-point Parkinson mutations of the Roc and COR domains are in close proximity. The analogous mutations in C. tepidum Roc-COR decrease the GTPase reaction rate, most likely due to a modification of the interaction between the Roc and COR domains.
复杂蛋白的Ras（Roc）属于Ras相关小G蛋白超家族，它总是与Roc（COR）结构域的C末端串联出现。这种Roc-COR串联在细菌和真核生物中都有发现。其最著名的成员是富含亮氨酸重复序列激酶LRRK2，它在帕金森病患者中发生突变并被激活。在这里，我们对嗜热绿菌的Roco蛋白进行了生物化学和结构研究。我们发现Roc与Ras高度同源，而COR结构域是一种二聚化装置。G结构域的并列和突变分析表明，Roc GTPase反应以核苷酸依赖的方式受到二聚化的刺激和/或调节。细菌和人类之间最保守的区域是Roc和COR之间的界面，Roc和COR结构域的单点帕金森突变就在附近。嗜热绿菌Roc-COR中的类似突变降低了GTPase反应速率，这很可能是由于Roc和COR结构域之间相互作用的改变。
