新vip3Aa基因的克隆、表达及其序列分析

克隆了Bt9816C的vip3A基因,并将测序结果提交到GenBank(序列号:AY945939)。该基因是一个新的vip3Aa基因,Bt杀虫晶体蛋白命名委员会将其命名为vip3Aa18。在大肠杆菌BL21中表达了该基因,生物测定结果表明纯化的Vip3Aa18蛋白对棉铃虫和甜菜夜蛾具有很高的杀虫活性。序列分析结果显示Vip3Aa18C端536至667位氨基酸残基间是一个糖类结合域,推测可能参与Vip3Aa18与敏感昆虫中肠受体结合;N端272至292位氨基酸残基间存在一个跨膜螺旋,可能与Vip3Aa18形成穿孔有关。此外,Vip3Aa18还可能具有一个二硫键。这些特殊区域和位点可能与其功能密切相关。

Cloning, Expressing and Sequence Analysis of a Novel vip3Aa Gene

The vip3A gene of Bt9816C was cloned and the sequencing result was submitted to GenBank (accession no.AY945939). The gene was identified as a novel vip3Aa gene, which was assigned name vip3Aa18 by the Bacillus thuringiensis delta-endotoxin nomenclature committee. Subsequently, vip3Aa18 was expressed in Escherichia coli BL21 and bioassay demonstrated that the purified recombinant Vip3Aa18 had high toxicity against Helicoverpa armigera and Spodoptera exigua. The results of sequence analysis revealed that a carbohydrate binding domain exists on the C-termini 536 to 667 residues of Vip3Aa18,which maybe participate in binding to midgut receptors in susceptible insects. Moreover, a transmembrane helices located on N-termini 272 to 292 residues was proposed responding for pore formation. Furthermore, a putative disulfide bond was found in the Vip3Aa18 sequence. The specific structures and sites of Vip3Aa18 sequence imply potential function.