Bogosian G, Bilyeu K, O'Neil J P
Animal Sciences Division, Monsanto Company, Chesterfield, MO 63198.
Gene. 1993 Oct 29;133(1):17-22. doi: 10.1016/0378-1119(93)90219-s.
Mutant strains selected as survivors of the lethal overexpression of a plasmid-encoded bovine somatotropin-beta-galactosidase fusion protein were found to include instances where an IS10 element had transposed from the chromosome into the fusion protein structural gene on the plasmid. Two distinct types of IS10 elements were found in these mutants, the well-known IS10R and a novel hybrid element composed of portions of both IS10R and IS10L. The strain in which the selection scheme was carried out had been constructed in a series of steps, including alteration of two loci by Tn10-mediated intramolecular transposition involving fusaric acid (FA) selection for loss of tetracycline resistance. Genetic dissection of this strain revealed that one of these altered loci was an origin for both types of IS10 elements, while the other locus was an origin for only IS10R elements. The finding that residual IS10 elements, left after FA selection for Tcs derivatives of Tn10-containing strains, can be a significant source of spontaneous mutation should be of interest to workers using strains that have been 'cured' of Tn10 in this way.
作为质粒编码的牛生长激素 - β - 半乳糖苷酶融合蛋白致死性过表达的幸存者而被选择的突变菌株，被发现存在IS10元件从染色体转座到质粒上融合蛋白结构基因中的情况。在这些突变体中发现了两种不同类型的IS10元件，即著名的IS10R和一种由IS10R和IS10L部分组成的新型杂交元件。进行选择方案的菌株是通过一系列步骤构建的，包括通过Tn10介导的分子内转座改变两个位点，其中涉及利用对fusaric acid（FA）的选择来实现四环素抗性的丧失。对该菌株的遗传分析表明，这些改变的位点之一是两种类型IS10元件的起源，而另一个位点仅是IS10R元件的起源。对于使用以这种方式“去除”Tn10的菌株的研究人员来说，在对含Tn10菌株的Tcs衍生物进行FA选择后留下的残余IS10元件可能是自发突变的重要来源这一发现应该是有意义的。
