猪口蹄疫病毒受体β8亚基的基因克隆与分子特征

Molecular Cloning and Characteristics of cDNA Encoding Porcine β8 Subunit for FMDV Receptor

口蹄疫病毒利用整联蛋白作为病毒受体进入宿主细胞。本试验在国际上首次从口蹄疫病毒感染猪的舌皮组织中克隆到了β8亚基基因,并对其核苷酸序列和推导的氨基酸序列进行了比较分析。猪β8亚基基因的编码区含有2 304个核苷酸,编码767个氨基酸,其中信号肽由42个氨基酸组成,胞外域由637个氨基酸组成,含有7个潜在的糖基化位点(NXT/NXS)和49个半胱氨酸残基,跨膜区由30个氨基酸组成,胞浆域由58个氨基酸组成,猪β8基因与牛、人、犬、猕猴、家鼠和挪威大鼠的β8基因核苷酸序列同源性分别为94.3%、91.4%、91.7%、91.4%、83.5%、83.5%,推导的氨基酸序列同源性分别为95.0%、91.8%、92.8%、91.5%、84.0%、84.8%。猪与牛β8亚基同源性最高。猪β8亚基存在复杂多变的二级结构,其中1-42、680-709位氨基酸区段疏水性较强,形成表面蛋白结构的可能性较小,分别是该亚基的信号肽和跨膜区。本试验为进一步深入研究β8亚基在口蹄疫感染过程中所扮演的角色奠定了基础。

Field isolates of foot-and-mouth disease virus （FMDV） are believed to use integrins as cellular receptors for virus internalization in vivo. In this study, we first cloned and sequenced the cDNA encoding porcine integrin β8 from the tongue keratinocytes of pig infected experimentally with FMDV. The 2 304 bp cDNA of porcine integrin β8 encodes a polypeptide of 767 amino acids consisting of a 42-residue putative signal peptide, a 637-residue ectodomain, a 30-residue transmembrane domain, and a 58-residue cytoplasmic domain. The ectodomain contains 7 potential N-linked glycosylation sites（NXT/NXS）and 49 cysteine residues. The nucleotide sequence similarity of integrin β8 between pig and cattle, human, dog, rhesus monkey, house mouse, Norway rat are 94.3%,91.4%,91.7%,91.4%,83.5% ,83.5%, and the amino acid sequence similarity are 95.0%,91.8%,92.8%,91.5%,84.0%,84.8%,respectively. The secondary structure of porcine β8 contains a-helix, β-sheet, β-turn and coil regions. The hydropathic analysis of the polypeptide revealed two hydrophobic domains,the signal peptide（1-42aa） and transmembrane domain （680-709aa）. This study will lay a foundation for understanding the interactions of FMDV with receptors.