MHCⅠ类分子BF2*0201递呈ALV-J表位结构和递呈机制解析  

Structure and Mechanism of ALV-J Epitope Presented by MHC ClassⅠMolecule BF2*0201

作　　者：贾玉生 李易霖 马露露 廖明 代曼曼 JIA Yusheng;LI Yilin;MA Lulu;LIAO Ming;DAI Manman(National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and Control,Guangdong Provincial Key Laboratory of Zoonosis Prevention and Control,College of Veterinary Medicine,South China Agricultural University,Guangzhou 510642,China)

机构地区：[1]华南农业大学兽医学院,人兽共患病防控制剂国家地方联合工程实验室,广东省动物源性人兽共患病预防与控制重点实验室,广州510642

出　　处：《畜牧兽医学报》2024年第7期3132-3142,共11页ACTA VETERINARIA ET ZOOTECHNICA SINICA

基　　金：国家自然科学基金面上项目(32172868);高等学校学科创新引智计划项目(D20008)。

摘　　要：MHC B2单倍型鸡对禽白血病病毒感染有较强抗性,这种抗病性可能与被MHC分子递呈的表位刺激活化的T细胞产生的免疫应答有关。本研究拟阐明MHCⅠ类分子BF2*0201递呈ALV-J表位结构和递呈机制。利用凝胶过滤层析筛选出能与MHCⅠ稳定结合的肽。利用晶体初筛试剂盒在体外培育肽和MHCⅠ的二元复合物晶体,并利用COOT、CCP4和PYMOL等软件对该晶体结构进行解析和分析。在这项研究中,作者发现二个与BF2*0201稳定结合的ALV-J CTL表位FVDFANRLI和SALQAFREV。得到一个优质晶体BF2*0201-SALQAFREV(SV9),其生长条件为1.0 mol·L^(-1)丁二酸(pH 7.0),0.1 mol·L^(-1)HEPES(pH 7.0),1%聚乙二醇单甲醚2000。解析高分辨率(1.72?)的BF2*0201-SV9复合物结构后发现BF2*0201抗原结合槽整体呈现弱负电性。保守的残基多位于抗原结合槽的两端,特异性氨基酸赋予BF2*0201中等大小的抗原结合槽。B、C和F口袋起着较重要的锚定作用,口袋残基和水分子与抗原多肽形成氢键作用,将其固定在抗原结合槽中。SV9表位构象中突出的P4-Gln和P7-Arg残基的构象特征表明该位点有被特异性TCR潜在识别的特性。BF2*0201-SV9复合物晶体结构特征有助于阐明B2单倍型MHCⅠ类分子BF2*0201递呈ALV-J表位的机制,有助于解释B2单倍型鸡对ALV存在抗性的原因,为抗病育种工作奠定理论基础。MHC B2 haplotype chickens are highly resistant to avian leukosis virus infection,and this resistance may be related to the activated T cell immune response stimulated by MHC molecule presented epitopes.This study aims to elucidate the structure and mechanism of ALV-J epitope presentation by the MHC classⅠmolecule BF2*0201.Peptides that can bind stably to MHCⅠwere screened by gel filtration chromatography.The complex crystals of the peptide and MHCⅠwere grown in vitro using a crystal primary screening kit,and the crystal structure was resolved and analyzed using COOT,CCP4 and PYMOL.In this study,we identified two ALV-J CTL epitopes FVDFANRLI and SALQAFREV that bind stably to BF2*0201.We obtained a high quality crystal BF2*0201-SALQAFREV(SV9)grown under the conditions of 1.0 mol·L^(-1) succinic acid(pH 7.0),0.1 mol·L^(-1) HEPES(pH 7.0),and 1%polyethylene glycol monomethyl ether 2000.We resolved the structure of the high-resolution(1.72)BF2*0201-SV9 complex and found that the BF2*0201 antigen-binding groove exhibits weak electronegativity overall.Conserved residues were located at both ends of the antigen-binding groove,and specific amino acids gave BF2*0201 a medium-sized peptide-binding groove.The B,C,and F pockets played an important anchoring role.The residues in pockets and water molecules formed hydrogen bonds with the antigenic polypeptide to anchor it to the peptide-binding groove,and the antigenic polypeptide was in an"M"-shaped conformation.The conformational features of the prominent Gln-4 and Arg-7 residues in the SV9 epitope conformation suggested potential recognition of this site by specific TCRs.The crystal structure of BF2*0201-SV9 complex can help to elucidate the mechanism of ALV-J epitope presented by BF2*0201,which can help to explain the reason for the resistance of B2 haplotype chickens to ALV,and lay a theoretical foundation for the breeding of resistance to the disease.

关 键 词：MHC BF2*0201 ALV-J 递呈机制 晶体结构 

分 类 号：S852.43[农业科学—基础兽医学]