ApNPV编码的DNA单链结合蛋白基因lef-3的克隆与分析

Cloning and Sequence Analysis of Single-Strand DNA-Binding Protein lef-3 Gene From Antheraea pernyi Nucleopolyhedrovirus

用随机克隆法,克隆得到了柞蚕核型多角体病毒(Antheraeapernyinucleopolyhedrovirus,ApNPV)PstⅠ和XhoⅠ片段,经序列分析表明,该片段含有完整的晚期表达因子3(lef3),与其它来源的lef3基因具有很高的同源性。ApNPVlef3基因的阅读框为1110bp,编码369个氨基酸,编码一种DNA单链结合蛋白(singlestrandedDNAbindingprotein,SSB)。lef3基因参与病毒DNA复制,是病毒DNA复制必不可少的蛋白质因子。LEF3的N-端有一个氨基酸保守序列区,推测此氨基酸序列保守区是LEF3的主要功能区。在lef3基因上游的互补序列有一编码127个氨基酸序列的不完全阅读框,根据同源性比较,此阅读框与黄杉毒蛾核型多角体病毒(Orgyiapseudotsugatanucleopolyhedrovirus,OpNPV)的ORFs73编码相似的基因,而在该片段的3′端其序列与近缘种OpNPV和云杉卷叶蛾多角体病毒(Choristoneurafumiferananucleopolyhedrovirus,CfNPV)没有同缘性,显示了ApNPV基因组结构有其固有的特点。

The gene encoding single-stranded DNA-binding protein(SSB) late expression factor 3(lef-3) was cloned from PstⅠ and XhoⅠ fragment of Antheraea pernyi nucleopolyhedrovirus(ApNPV) genome. Nucleotide sequence analysis of fragment revealed that lef-3 has a whole open reading frame of 1 110 bp encoding 369 amino acids,and has high homology on amino acid level compared to the LEF-3 from other baculovirus. LEF-3 is identified as being essential for baculovirus DNA replication. LEF-3 proteins contain a conserved pattern of amino acids similar to this SSB motif in their amino-terminal regions, indicating that this region may be important for LEF-3 function. Upstream the lef-3 there is a sequence encoding 127 amino acids , but it is a partial open reading frame. According to homologous analysis this nucleotide sequence is similar to ORFs73 of OpNPV. At 3′end there is no homologous sequence compared to Orgyia pseudotsugata nucleopolyhedrovirus(OpNPV) and Choristoneura fumiferana nucleopolyhedrovirus (CfNPV) ,which indicates particularity of ApNPV.