埃博拉病毒入侵:人TIM分子的结构与结合PS的分子基础  

Crystal structures of human TIM members:Ebolavirus entry-enhancing receptors

作　　者：王寒[1] 齐建勋[1] 刘宁宁[1] 李燕[1] 高俊[2] 张廷虹[1] 柴彦[1] 高峰[3] 张浩[4] 李向东[2] 叶昕[1] 严景华[1,5] 逯光文[6] 高福[1,7,8] 

机构地区：[1]中国科学院微生物研究所病原微生物与免疫学重点实验室,北京100101 [2]中国农业大学农业生物技术国家重点实验室,北京100193 [3]中国科学院遗传与发育生物学研究所,北京100101 [4]安徽大学生命科学院,合肥230039 [5]中国科学院微生物研究所微生物生理与代谢工程重点实验室,北京100101 [6]四川大学华西医院生物治疗国家重点实验室,成都610041 [7]中国疾病预防控制中心病毒病预防控制所,北京102206 [8]中国科学院北京生命科学研究院免疫与健康联合研究中心,北京100101

出　　处：《科学通报》2015年第35期3438-3453,共16页Chinese Science Bulletin

基　　金：国家自然科学基金(81590761);中国科学院战略重点研究项目(XDB08020100);中国科学院院长基金埃博拉病毒研究特别项目资助

摘　　要：研究表明,人T细胞免疫球蛋白黏蛋白(human T-cell immunoglobulin and mucin domain,h TIM)受体分子能够促进包括埃博拉病毒在内的很多囊膜病毒的入侵.h TIM介导的病毒入侵过程高度依赖于位于受体分子胞外区远膜端的免疫球蛋白V区(immunoglobulin variable(Ig V)-like)结构域与病毒囊膜中磷脂酰丝氨酸(phosphotidylserine,PS)的特异性相互作用.人类TIM家族共有3个成员:h TIM-1,h TIM-3和h TIM-4.虽然相应的小鼠TIM分子的结构已经解析,但h TIM分子的Ig V结构特征及其识别PS的分子基础仍然未知.同时,有研究表明,引起西非大规模埃博拉疫情爆发的2014-扎依尔-埃博拉病毒可能较其先前流行株具有更强的致病能力.但目前尚未有2014-扎依尔-埃博拉病毒利用h TIM分子入侵细胞及其与1976-扎依尔-埃博拉病毒的入侵能力比较的研究报道.本研究证明了整合有1976-和2014-扎依尔-埃博拉病毒囊膜糖蛋白(glycoprotein,GP)的假病毒均可以利用h TIM-1和h TIM-4入侵细胞,并且表现出相近的入侵效率.进一步证明了h TIM分子不与埃博拉病毒GP蛋白直接相互作用,而是通过结合病毒囊膜中的PS分子而促进病毒感染.随后解析了3种h TIM分子Ig V结构域的高分辨率晶体结构以及h TIM-4与磷酸丝氨酸的复合物晶体结构.令人意外的是,3种h TIM分子的PS结合槽呈现出各自不同的局部结构特征且在目前已解析结构的小鼠同源分子中均未被观察到.这些结构特征很可能提示h TIM分子具有不同于小鼠同源分子、且彼此间亦各不相同的PS识别模式.上述结构和功能数据丰富了我们对h TIM结合PS的分子基础的认识,从而将帮助我们更深入地了解埃博拉和相关囊膜病毒利用h TIM受体入侵细胞的分子机制.Human T-cell immunoglobulin and mucin domain（h TIM） receptor was recently identified as the entry-enhancing receptor for various enveloped viruses,including ebolavirus. This h TIM-mediated virus entry is highly dependent on the immunoglobulin variable（Ig V）-like domain of the receptor and on the specific interactions between h TIM Ig V and the phosphotidylserine（PS） moieties on the viral envelope. There are three members in the h TIM family,including h TIM-1,-3,and-4. However,their Ig V domain structures and the PS binding basis remain elusive thus far,though their murine homologues have been structurally well defined. In addition,it is suspected that the 2014-Zaire-ebolavirus,which has caused the largest pandemic ever recorded last year in West Africa,might have different pathogenic capacity from the earlier isolates. Nevertheless,it remains uninvestigated if the 2014-Zaire-ebolavirus can recognize hT IMs to enhance virus infection similarly to the previously tested 1976-Zaire-ebolavirus. In this study,we first showed that pseudoviruses incorporating either the 1976-or the 2014-Zaire-ebolavirus glycoprotein（GP） exhibit similarly enhanced cell entry via h TIM-1 and-4,but not with h TIM-3. Though 2014-GP mutations are suspected giving rise to a higher virulence,analogous entry rate was observed for 1976- and 2014-GP. We further showed that the h TIM receptors do not directly interact with either the mucin-deleted or the mucin-reserved intact ebolavirus GP,and that h TIM-1 and-4 engage envelope PS to facilitate the viral infection. We then solved all the three h TIM Ig V-domain structures as well as the h TIM-4/phosphoserine complex structure. Several unexpected regional features,which have not been observed in any of the mouse homologues,were identified in the individual PS-binding clefts of the three h TIMs,including a shortened FG loop in hT IM-1,a novel metal binding site in h TIM-3,and an alternative conformation for the CC’ loop in hT IM-4. These characteristics astonishingly indicated varia

关 键 词：人T细胞免疫球蛋白黏蛋白分子 蛋白质晶体结构 埃博拉病毒入侵 磷脂酰丝氨酸结合机制 

分 类 号：R373[医药卫生—病原生物学]