Caramori T, Albertini A M, Galizzi A
Dipartimento di Genetica e Microbiologia A. Buzzati-Traverso, Università degli Studi di Pavia, Italy.
Gene. 1991 Feb 1;98(1):37-44. doi: 10.1016/0378-1119(91)90101-g.
The parasporal crystal of Bacillus thuringiensis is composed of polypeptides highly toxic to a number of insect larvae. The structural genes (cryIA) encoding the Lepidoptera-specific toxin from different bacterial strains diverge primarily in a single hypervariable region, whereas the N-terminal and C-terminal parts of the proteins are highly conserved. In this report, we describe the generation of hybrid genes between two cryIA genes. Two truncated cryIA genes were cloned in a plasmid vector in such way as to have only the hypervariable region in common. The two truncated cryIA genes were separated by the tetracycline-resistance determinant (or part of it). In vivo recombination between the hypervariable regions of the cryIA genes reconstituted an entire hybrid cryIA gene. Direct sequence analysis of 17 recombinant plasmids identified eleven different crossover regions which did not alter the reading frame and allowed the production of eight different hybrid proteins. The recombination events were independent from the RecA function of Escherichia coli. Some of the hybrid gene products were more specific in their insecticidal action and one had acquired a new biological activity.
苏云金芽孢杆菌的伴孢晶体由对多种昆虫幼虫具有高毒性的多肽组成。编码来自不同菌株的鳞翅目特异性毒素的结构基因（cryIA）主要在单个高变区存在差异，而蛋白质的N端和C端部分高度保守。在本报告中，我们描述了两个cryIA基因之间杂交基因的产生。两个截短的cryIA基因以仅具有共同高变区的方式克隆到质粒载体中。两个截短的cryIA基因被四环素抗性决定簇（或其一部分）隔开。cryIA基因高变区之间的体内重组重建了一个完整的杂交cryIA基因。对17个重组质粒的直接序列分析确定了11个不同的交叉区域，这些区域没有改变阅读框，并允许产生8种不同的杂交蛋白。重组事件独立于大肠杆菌的RecA功能。一些杂交基因产物在杀虫作用上更具特异性，并且有一种获得了新的生物学活性。
