Chi mutation in a transposon and the orientation-dependence of Chi phenotype.
Chi mutation in a transposon and the orientation-dependence of Chi phenotype.
复制标题
转座子中的 Chi 突变和 Chi 表型的方向依赖性。
作者：
E. Yagil;N. Dower;D. Chattoraj;M. Stahl;C. Pierson;F. Stahl
Chi是一种通过大肠杆菌RecBC途径刺激重组的元素，可由转座子Tn5的自发突变产生。当噬菌体λ处于一个方向时，突变转座子具有Chi+表型（大斑块和转座子附近的高交换率）。然而，在另一个方向上，转座子不赋予Chi+表型。转座子的移动性使我们能够证明突变体Tn5的Chi+取向在lambda的不同位置是相同的。其中包括基因J附近的一个位点，在gam 69处有一个，在gam 73处有一个，在R 95.7到99.5之间有几个。在R的右边，突变转座子只能在一个方向上发现，这赋予了Chi+表型。我们推测Tn5在该区域的另一个方向对lambda是致命的。Chi+表型的定向依赖性也揭示了Tn5在lambda中的翻转。
Chi, an element that stimulates recombination via the E. coli RecBC pathway, can arise by spontaneous mutation in the transposon Tn5. When in phage lambda in one orientation, the mutant transposon confers Chi+ phenotype (large plaque and a high rate of exchange near the transposon). In the other orientation, however, the transposon does not confer Chi+ phenotype. The mobility of the transposon allows us to show that the Chi+ orientation of the mutant Tn5 is the same at different locations in lambda. These include a site near gene J, one in gam at 69, one to the right of gam at 73 and several to the right of R between 95.7 and 99.5. To the right of R, the mutant transposon could be found in only one orientation, that which confers Chi+ phenotype. We speculate that the other orientation of Tn5 in that locale is lethal to lambda. The orientation-dependence of Chi+ phenotype also revealed that Tn5 flip-flops in lambda.