Yagil E, Dower N A, Chattoraj D, Stahl M, Pierson C, Stahl F W
Genetics. 1980 Sep;96(1):43-57. doi: 10.1093/genetics/96.1.43.
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.
χ是一种通过大肠杆菌RecBC途径刺激重组的元件，可通过转座子Tn5中的自发突变产生。当以一种方向存在于噬菌体λ中时，突变转座子赋予χ⁺表型（大噬菌斑以及转座子附近的高交换率）。然而，在另一种方向时，转座子不赋予χ⁺表型。转座子的可移动性使我们能够证明，突变型Tn5的χ⁺方向在λ的不同位置是相同的。这些位置包括基因J附近的一个位点、69处gam中的一个位点、73处gam右侧的一个位点以及95.7至99.5之间R右侧的几个位点。在R右侧，只能在赋予χ⁺表型的那个方向找到突变转座子。我们推测，Tn5在该区域的另一个方向对λ是致死的。χ⁺表型的方向依赖性还表明，Tn5在λ中会发生翻转。
