Iida S, Hiestand-Nauer R
Cell. 1986 Apr 11;45(1):71-9. doi: 10.1016/0092-8674(86)90539-8.
The crossover sites for site-specific C inversion consist of imperfect 12 bp inverted repeats with the dinucleotide TT at the center of symmetry. The phage P1 Cin recombinase acts not only at these cix sites but also less efficiently at cix-related sequences called quasi-cix sites, cixQ. When cixQ contains a central dinucleotide TT, crossover occurs in vivo at the 2 bp sequence TT in the normal and the quasi-cix sites. If cixQ carries only one T residue, inversion-associated localized conversion can occur at the mismatched position within the 2 bp sequence. The results indicate that Cin generates 2 bp staggered cuts in vivo and that reciprocal strand exchanges occur at these 2 bp crossover sequences.
位点特异性C倒位的交叉位点由不完美的12bp反向重复序列组成，对称中心为二核苷酸TT。噬菌体P1 Cin重组酶不仅作用于这些cix位点，而且在与cix相关的序列（称为准cix位点cixQ）上作用效率较低。当cixQ包含中心二核苷酸TT时，体内在正常和准cix位点的2bp序列TT处发生交叉。如果cixQ仅携带一个T残基，则在2bp序列内的错配位置可发生与倒位相关的局部转换。结果表明，Cin在体内产生2bp交错切口，并且在这些2bp交叉序列处发生相互的链交换。
