Chen Liqing, DiGiammarino Enrico, Zhou Xiaoyin E, Wang Yujun, Toh Diana, Hodge Thomas W, Meehan Edward J
Laboratory for Structural Biology, Department of Chemistry, Graduate Programs of Biotechnology, Chemistry and Materials Science, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.
J Biol Chem. 2004 Sep 17;279(38):40204-8. doi: 10.1074/jbc.M407114200. Epub 2004 Jul 19.
Rab GTPases and their effectors facilitate vesicular transport by tethering donor vesicles to their respective target membranes. Rab9 mediates late endosome to trans-Golgi transport and has recently been found to be a key cellular component for human immunodeficiency virus-1, Ebola, Marburg, and measles virus replication, suggesting that it may be a novel target in the development of broad spectrum antiviral drugs. As part of our structure-based drug design program, we have determined the crystal structure of a C-terminally truncated human Rab9 (residues 1-177) to 1.25-A resolution. The overall structure shows a characteristic nucleotide binding fold consisting of a six-stranded beta-sheet surrounded by five alpha-helices with a tightly bound GDP molecule in the active site. Structure-based sequence alignment of Rab9 with other Rab proteins reveals that its active site consists of residues highly conserved in the Rab GTPase family, implying a common catalytic mechanism. However, Rab9 contains seven regions that are significantly different in conformation from other Rab proteins. Some of those regions coincide with putative effector-binding sites and switch I and switch II regions identified by structure/sequence alignments. The Rab9 structure at near atomic resolution provides an excellent model for structure-based antiviral drug design.
Rab GTP酶及其效应蛋白通过将供体囊泡拴系到各自的靶膜上来促进囊泡运输。Rab9介导晚期内体到反式高尔基体的运输，最近被发现是人类免疫缺陷病毒1型、埃博拉病毒、马尔堡病毒和麻疹病毒复制的关键细胞成分，这表明它可能是广谱抗病毒药物开发中的一个新靶点。作为我们基于结构的药物设计项目的一部分，我们已经确定了C端截短的人Rab9（1-177位残基）的晶体结构，分辨率为1.25埃。整体结构显示出一种特征性的核苷酸结合折叠，由一个六链β折叠片层组成，周围环绕着五个α螺旋，活性位点有一个紧密结合的GDP分子。Rab9与其他Rab蛋白基于结构的序列比对显示，其活性位点由Rab GTP酶家族中高度保守的残基组成，这意味着存在共同的催化机制。然而，Rab9包含七个与其他Rab蛋白构象显著不同的区域。其中一些区域与通过结构/序列比对确定的假定效应蛋白结合位点以及开关I和开关II区域重合。接近原子分辨率的Rab9结构为基于结构的抗病毒药物设计提供了一个极好的模型。
