Unité de Biochimie Microbienne, Institut Pasteur, URA 1300 du Centre National de la Recherche Scientifique, 25, rue du Docteur Roux, 75724 Paris Cedex 15, France.
Appl Environ Microbiol. 1993 Nov;59(11):3922-7. doi: 10.1128/aem.59.11.3922-3927.1993.
The cryIVA and cryIVB genes, encoding the 125- and 135-kDa proteins, respectively, of Bacillus thuringiensis subsp. israelensis, were cloned either alone or together into a shuttle vector and expressed in a nontoxic strain of B. thuringiensis subsp. israelensis. The CryIVB protein was produced at a high level during sporulation and accumulated as inclusions; in contrast, the CryIVA polypeptide did not form such structures unless it was cloned on a higher-copy-number plasmid. Transcriptional fusions between the cryIVA or cryIVB gene promoter and the lacZ gene were constructed. The poor synthesis of CryIVA was not due to a poor efficiency of transcription from the cryIVA gene promoter. Mosquitocidal assays performed with purified inclusions showed that CryIVA was toxic for larvae of the species Aedes aegypti, Anopheles stephensi, and Culex pipiens, whereas CryIVB displayed activity only toward Aedes aegypti and Anopheles stephensi. The activity of inclusions containing both polypeptides was higher than that of single-peptide inclusions but was not as high as that of the native crystals, which contain at least four polypeptides.
cryIVA 和 cryIVB 基因分别编码苏云金芽孢杆菌亚种 israelensis 的 125kDa 和 135kDa 蛋白，被单独或一起克隆到穿梭载体中，并在苏云金芽孢杆菌亚种 israelensis 的无毒菌株中表达。CryIVB 蛋白在孢子形成过程中大量产生，并以包含体的形式积累；相比之下，除非 CryIVA 多肽被克隆到更高拷贝数的质粒上，否则它不会形成这种结构。CryIVA 或 cryIVB 基因启动子与 lacZ 基因之间的转录融合被构建。CryIVA 合成不良不是由于 cryIVA 基因启动子转录效率低下所致。用纯化的包含体进行的杀蚊活性测定表明，CryIVA 对埃及伊蚊、致倦库蚊和淡色库蚊的幼虫具有毒性，而 CryIVB 仅对埃及伊蚊和致倦库蚊具有活性。含有两种多肽的包含体的活性高于单一肽包含体的活性，但不如含有至少四种多肽的天然晶体的活性高。
