EB病毒蛋白BNLF2a阻止抗原转运蛋白TAP的构象变化  

Epstein-Barr viral protein BNLF2a suppresses the conformational change of antigenic peptide transporter TAP

作　　者：尹利敏 林嘉成 YIN Li-Min;LIN Jia-Cheng(Key Laboratory of Tumor Microbiology in Fujian Province, Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Department of Pathogen Biology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian 350122, China)

机构地区：[1]福建医科大学基础医学院消化道恶性肿瘤教育部重点实验室肿瘤微生物福建省重点实验室病原生物学系

出　　处：《微生物学通报》2019年第6期1443-1451,共9页Microbiology China

基　　金：福建省自然科学基金青年基金项目(2015J05156);国家自然科学基金青年基金项目(81501755)~~

摘　　要：【背景】EB病毒是一个常见的病原,它能引起霍奇金淋巴瘤、伯基特淋巴瘤以及胃癌、鼻咽癌。该病毒编码的膜蛋白BNLF2a抑制抗原转运蛋白TAP (Transporter associated with antigen processing)从而逃逸T细胞的清除。TAP属于ABC(ATP-bindingcassette)转运蛋白超家族,是由TAP1和TAP2两个亚基构成的。TAP通过ATP提供能量,跨膜转运抗原多肽,这一过程伴随着构象变化。【目的】旨在揭示BNLF2a是否影响TAP的构象变化。【方法】TAP蛋白核酸结合结构域的二聚体界面的D-loop进行点突变,引入半胱氨酸。在表达和不表达BNLF2a情况下,采用氧化性的二价铜离子交联半胱氨酸,并通过Westernblot对比TAP的半胱氨酸形成二硫键的比例。【结果】BNLF2a表达使TAP被交联的比例增高。【结论】BNLF2a可能将TAP稳定在核苷酸结合结构域二聚化的构象,从而同时抑制ATP和抗原多肽结合到TAP上来。[Background] Epstein-Barr virus(EBV) is a common pathogen causing Burkitt’s lymphoma,Hodgkin’s disease, gastric cancer and nasopharyngeal carcinoma. A membrane protein BNLF2 a encoded by EBV inhibits antigen transportation by transporter associated with antigen processing(TAP) and thereby evades the elimination by cytotoxic T cells. TAP is a member of the ATP-binding cassette(ABC) superfamily and composed of two subunits of TAP1 and TAP2. Using the energy of ATP hydrolysis, TAP transports antigenic peptides across the membrane with a conformational change.[Objective] The aim of this study was to study if BNLF2 a affects the conformational switch of TAP.[Methods] Cysteines were introduced into the D-loop at the interface of TAP’s nucleotide binding domains. TAP were cross-linked by oxidizing agent Cu(II). The ratios of disulfide formed TAP were compared in the presence or absence of BNLF2 a by western blot.[Results] The expression of BNLF2 a increased the ratio of cross-linked TAP.[Conclusion] BNLF2 a appears to stabilize TAP in the nucleotide binding domains dimerized conformation and thereby inhibit both of ATP and antigenic peptide binding to TAP.

关 键 词：EB病毒 BNLF2a TAP ABC转运蛋白 抗原多肽 

分 类 号：R373[医药卫生—病原生物学]