Structural and Biochemical Analyses of Swine Major Histocompatibility Complex Class I Complexes and Prediction of the Epitope Map of Important Influenza A Virus Strains
Structural and Biochemical Analyses of Swine Major Histocompatibility Complex Class I Complexes and Prediction of the Epitope Map of Important Influenza A Virus Strains
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猪主要组织相容性复合物I类复合物的结构和生化分析及重要甲型流感病毒株表位图的预测
DOI：
10.1128/jvi.00119-16
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发表时间：
2016-08-01
影响因子：
5.4
通讯作者：
Xia, Chun
中科院分区：
文献类型：
--
作者：
Fan, Shuhua;Wu, Yanan;Xia, Chun
由于缺乏肽-猪白细胞抗原I类（pSLA I）复合物结构，给猪细胞毒性T淋巴细胞（CTL）免疫的研究和消除重要猪病毒性疾病（如甲型流感病毒（IAV））的分子疫苗开发带来了困难。本研究通过对中国黑山猪28个SLA I等位基因的克隆和比较，得到了pSLA-3* hs 0202。SLA-3* hs 0202与来自2009年大流行猪H1N1毒株的sβ 2 m和KMNTQFTAV（血凝素[HA]-KMN 9）肽的结合在结构中清楚地显示出与HA-KMN 9肽的两种不同构象，这被认为有利于刺激广谱CTL免疫应答。值得注意的是，我们发现不同的HA-KMN 9构象不仅是由肽结合沟（PBG）中残基侧链的柔性引起的，而且还由形成PBG的α1和α2螺旋的偏斜引起的。此外，丙氨酸扫描和圆二色性（CD）光谱证实，B，D和F口袋在决定SLA-3* hs 0202的肽结合基序中发挥关键的生物化学作用。基于生化参数和与其他已知的主要组织相容性复合物I类（MHC-I）结构中的类似口袋的比较，通过体外重折叠和多个突变肽确定SLA-3* hs 0202的基本基序为X-（M/A/R）-（N/Q/R/F）-X-X-X-X-X-（V/I）。最后，从重要的IAV毒株中鉴定出28个SLA-3* hs 0202限制性候选表位，其中两个已在人类中发现为HLA-A*0201特异性IAV表位。对pSLA-3* hs 0202的结构和生化特性的研究有助于疫苗的开发，以控制猪IAV。我们结晶并解析了第一个SLA-3结构SLA-3* hs 0202，发现它可以呈现具有两种不同构象的相同IAV肽。与先前的发现不同，这些发现表明可变肽构象仅由凹槽中侧链的柔性引起，α1和α2螺旋的偏斜在SLA-3* hs 0202中的不同肽构象中很重要。通过一系列的结构和生化分析，确定SLA-3* hs 0202的基本基序为X-（M/A/R）-（N/Q/R/F）-X-X-X-X-X-（V/I），并从重要的IAV毒株中鉴定出28个SLA-3* hs 0202限制性表位候选者。我们相信我们的pSLA-3* hs 0202的结构和分析可以帮助疫苗的开发，以控制猪IAV。
ABSTRACT The lack of a peptide-swine leukocyte antigen class I (pSLA I) complex structure presents difficulties for the study of swine cytotoxic T lymphocyte (CTL) immunity and molecule vaccine development to eliminate important swine viral diseases, such as influenza A virus (IAV). Here, after cloning and comparing 28 SLA I allelic genes from Chinese Heishan pigs, pSLA-3*hs0202 was crystalized and solved. SLA-3*hs0202 binding with sβ2m and a KMNTQFTAV (hemagglutinin [HA]-KMN9) peptide from the 2009 pandemic swine H1N1 strain clearly displayed two distinct conformations with HA-KMN9 peptides in the structures, which are believed to be beneficial to stimulate a broad spectrum of CTL immune responses. Notably, we found that different HA-KMN9 conformations are caused, not only by the flexibility of the side chains of residues in the peptide-binding groove (PBG), but also by the skewing of α1 and α2 helixes forming the PBG. In addition, alanine scanning and circular-dichroism (CD) spectra confirmed that the B, D, and F pockets play critical biochemical roles in determining the peptide-binding motif of SLA-3*hs0202. Based on biochemical parameters and comparisons to similar pockets in other known major histocompatibility complex class I (MHC-I) structures, the fundamental motif for SLA-3*hs0202 was determined to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) by refolding in vitro and multiple mutant peptides. Finally, 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains, and two of them have been found in humans as HLA-A*0201-specific IAV epitopes. Structural and biochemical illumination of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine. IMPORTANCE We crystalized and solved the first SLA-3 structure, SLA-3*hs0202, and found that it could present the same IAV peptide with two distinct conformations. Unlike previous findings showing that variable peptide conformations are caused only by the flexibility of the side chains in the groove, the skewing of the α1 and α2 helixes is important in the different peptide conformations in SLA-3*hs0202. We also determined the fundamental motif for SLA-3*hs0202 to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) based on a series of structural and biochemical analyses, and 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains. We believe our structure and analyses of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine.