马立克氏病病毒Ⅰ型CVI988/Rispens疫苗株UL13激酶结构域分析及其偏嗜密码子片段在大肠杆菌中的表达

Kinase domain analysis of MDV-1 CVI988/Rispens UL13 and preferredcodon fragments expression in Escherichia coli

【目的】寻找MDV-1 UL13激酶催化中心,并体外表达UL13,以便研究UL13蛋白激酶的功能。【方法】用PCR方法从CVI988疫苗株基因组中扩增UL13基因,利用GENEART(www.gcua.de)分析UL13在大肠杆菌中表达时密码子的偏嗜性;通过DNAstar抗原性分析确定UL13的高抗原性片段,进行原核表达,并以切胶免疫方法免疫小鼠制备多抗血清;通过NCBI的protein blast功能及Cn3D 4.1在线软件分析UL13保守结构域。【结果】PCR扩增出UL13基因,序列分析结果表明,UL13的259～400aa、431～513aa两个片段抗原性强,且稀有密码子较少;保守结构域分析发现UL13催化中心主要位于152～297氨基酸残基间,且在激酶SubdomainⅦ的保守甘氨酸残基被丝氨酸替代,SubdomainⅧ的保守非极性脯氨酸残基被极性半胱氨酸残基替换。利用大肠杆菌表达的UL13第259～400aa片段免疫小鼠制备出多抗血清能与真核表达产物反应。【结论】MDV-1UL13催化中心主要位于152～297氨基酸残基间,体外表达的基因产物诱导机体产生了抗UL13激酶的特异性抗体。

[Objective]To find catalytic center of MDV-1 UL13 and express it in vitro to investigate the function of UL13 kinase. [Methods] UL13 gene was amplified by polymerase chain reaction （PCR） from MDV-1 CVI988/Rispens strain. The codon bias and antigenicity of UL13 in Escherichia coli was analyzed by online service GENEART （www.gcua.de）and DNAstar software respectively. Then the UL13 truncated fragments were expressed in Escherichia coli, and mice were immunized with the expressed Glutathione S Transferase fusion protein. The conserved domain was analyzed with protein blast and Cn3D 4.1 online software of National Center for Biotechnology Information. [Results] UL13 gene was successfully amplified. The sequence analysis suggests that 259-400 and 431-513 amino acid residues are low abundance for rare codon and strong antigenicity in UL13. Result of conserved domain analysis demonstrated that 152-297 residue iskinase catalytic center of UL13. However, conserved glycin in kinase subdomain Ⅶ for most protein kinase was replaced by serine in UL13 and proline in kinase subdomain Ⅷ replaced by cysteine. The serum from mice immunized with truncated fragment, 259-400 amino acids, could react with recombinant UL13 protein expressed in insect cells in immunofluorenscence assay. [Conclusion] The 152-297 residue is kinase catalytic center of MDV-1 UL13; UL13 protein expressed in vitro induced specific antibodies against UL13.