Haffter P, Bickle T A
Department of Microbiology, Basel University, Switzerland.
EMBO J. 1988 Dec 1;7(12):3991-6. doi: 10.1002/j.1460-2075.1988.tb03287.x.
Cin is a member of the hin family of complementing site-specific recombinases which regulate the alternate expression of genes by inverting DNA segments. Common characteristics of this family of recombination systems are the requirement for an enhancer-like element in cis and the specificity for inversely oriented recombination sites on the same DNA molecule. We have isolated two mutants of the Cin recombinase which will efficiently recombine a substrate lacking the enhancer. In addition, these mutant proteins also catalyse efficient recombination between sites in direct orientation or on different DNA molecules. Both mutations are due to single amino acid substitutions at different positions in the protein and the two mutants have slightly different phenotypes. The finding that the loss of enhancer dependence is coupled to a change in topological specificity leads us to conclude that the enhancer determines the specificity of the system for DNA inversion.
Cin是互补位点特异性重组酶hin家族的成员，该家族通过反转DNA片段来调节基因的交替表达。这个重组系统家族的共同特征是顺式需要一个增强子样元件，以及对同一DNA分子上反向排列的重组位点具有特异性。我们分离出了Cin重组酶的两个突变体，它们能有效地重组缺乏增强子的底物。此外，这些突变蛋白还能催化同向排列的位点之间或不同DNA分子上的位点之间的有效重组。这两个突变都是由于蛋白质中不同位置的单个氨基酸替换引起的，并且这两个突变体具有略有不同的表型。增强子依赖性的丧失与拓扑特异性的改变相关联，这一发现使我们得出结论，增强子决定了该系统对DNA反转的特异性。
