苏云金芽胞杆菌营养期杀虫蛋白基因特性分析

Characteristic Analysis of Vegetative Insecticidal Protein Gene from Bacillus thuringiensis

营养期杀虫蛋白是在苏云金芽胞杆菌营养期中发现的一种非晶体状胞外杀虫蛋白 .通过Southern杂交的基因定位实验 ,证实了营养期杀虫蛋白基因并非位于染色体和环型质粒上 ;在 2 0个不同血清型的 2 3种菌株中 ,营养期杀虫蛋白基因的存在率为 5 6 5 % (13 2 3) .同时对随机选择的 3个不同亚种菌株进行基因克隆和序列分析 ,表明其基因具有相当高的同源性 .运用生物信息技术 ,对营养期杀虫蛋白多肽进行了功能结构域比对分析 ,发现这 789多肽蛋白的N端 31至 15 0残基之间存在一种趋化信号传导因子相似序列 ,C端 5 36至 6 6 6残基之间则存在着纤维素结合结构域相似肽 .上述结果提示 ,营养期杀虫蛋白基因在苏云金芽胞杆菌天然菌株中高度保守并较为广泛分布 ,其编码蛋白的特殊结构提示了营养期杀虫蛋白潜在的功能特性 ,为进一步研究营养期杀虫蛋白奠定了基础 .

Vegetative insecticidal protein (VIP) is a non-crystal and extracellular toxic protein discovered at the vegetative stage of Bacillus thuringiensis strain. Using Southern blot of gene localization, vegetative insecticidal protein gene was determined neither on chromosome nor circle plasmids. Among the 23 strains of 20 serovars, the occurrence of vegetative insecticidal protein gene was 56.5% (13 positive in 23). Meanwhile, the homology of three vip genes which cloned and sequenced from random different serovar strains was very high. Furthermore, the blast results of the functional domains among vegetative insecticidal protein peptides by the bioinformation soft showed that a similar domain of chemotaxis sensory transducer exists on the N-termini 31 to 150 residues of 789 residues, and a cellulose binding domain from 536 to 666 residues on the C- termini. In the conclusion, these results indidate that vegetative insecticidal protein gene is highly conserved and is distributed broader in the natural strains of Bacillus thuringiensis, and the specific structure of its coded sequence implied potential function,which contributed to further making vegetative insecticidal protein clear.