家蚕质型多角体病毒(苏州株)基因组片段8 cDNA克隆与分析

Cloning and Sequence Analysis of Segment 8 cDNA from Bombyx mori cytoplasmic polyhedrosis virus 1 (strain Suzhou)

为研究家蚕质型多角体病毒(BmCPV1)的遗传与变异、探讨S8片段的功能,通过RT-PCR克隆BmCPV1苏州株(BmCPV1-SZ)S8的cDNA,并对其核苷酸序列(GenBank登录号:GQ150539)和编码的氨基酸序列进行生物信息学分析。结果显示:S8由1 328 bp构成,具有一个编码390个氨基酸残基的开放阅读框;在BmCPV1-SZ S8的编码氨基酸序列与BmCPV1-I和BmCPV1-H的一致性达93%,但与其他非CPV1型的相似程度较低;在推导的蛋白的氨基酸序列中间区域,具有E-丰富和P-丰富的区域,其局部区域的氨基酸序列与某些蛋白的功能(细胞周期控制、蛋白降解和RNA降解)区域的序列具有一定的相似性;结构域家族分析显示,BmCPV1-SZ S8编码蛋白属GcrA家族,具有与DNA结合的HTH结构域。Blocks分析显示,S8编码蛋白同时具有DNA聚合酶家族、RNA聚合酶2的结构功能域;高级结构分类显示,S8编码蛋白具有与TIM桶酶、肽酶、核苷三磷酸水解酶相似的同源结构。推测该蛋白具有转录调控因子和多功能酶的功能。基于S8编码的氨基酸序列的进化分析显示,相同类型的CPV聚为一类,同一宿主不同类型的CPV相距较远,推测CPV主要根据其类型聚类,而宿主昆虫对聚类的影响相对较小。

For further research on heredity and mutation of Bombyx mori cytoplasmic polyhedrosis virus 1（BmCPV1）,as well as the function of the Segment 8 of BmCPV1（BmCPV1 S8）.The cDNA of Segment 8 from the BmCPV1 strain Suzhou（BmCPV1-SZ） was amplified by RT-PCR technique,after sequencing,we analyzed the nucleotide and deduced amino acid sequences with the help of bioinformatics methods（GenBank No GQ150539）.Firstly,the outcome of analysis illustrated that segment 8 consisted of 1328 bp,encoding 390 amino acid residues and performed the higher similarity with BmCPV1 and BmCPV1-H based on amino acid sequences,approaching 93%,whereas had the much lower similarity with other un-CPV1s;Secondly,the middle region of deduced amino acid possessed the rich glutamic acid and Proline,meanwhile,some of the amino acid sequences in the local region of BmCPV1-SZ S8 showed a certain similarity with the functional area（cell cycle controlling,protein degradation and RNA degradation）of some proteins;In addition,domain analysis illustrated that BmCPV1-SZ S8 encoded the protein belong to GcrA family,which contains HTH domain for combining the specific DNA sequences;Then Blocks analysis elucidated that BmCPV1-SZ S8 protein as well as possessed some functional domains including DNA polymerase family and RNA polymerase 2 domain;After these,structural classification prediction indicated that BmCPV1-SZ S8 protein had the similar tertiary structure with TIM Barrel enzyme,peptidase and nucleotide triphosphate hydrolases.The above predictions speculate that this protein could perform the function related to transcriptional regulatory factor and multi-functional enzyme.Finally,evolutionary analysis based on BmCPV1-SZ S8 protein showed that the same type of CPVs could be clustered together,while the different type ones with same host were evolutionarily distant.Consequently,we speculated that CPVs were clustered mainly due to the types not the host insects