Martinez E, de la Cruz F
Departmento de Biologia Molecular, Universidad de Cantabria, Santander, Spain.
Mol Gen Genet. 1988 Feb;211(2):320-5. doi: 10.1007/BF00330610.
The IncW plasmid R388 and the DNA region of Tn21 containing the Smr and the Sur genes are capable of RecA-independent recombination. This recombination occurs at a relatively high frequency (up to 10(-4) recombinants per recipient molecule) and results in integration of the two plasmids. No detectable repeats are formed in the process. The crossover points have been confined to a 0.4-kb homologous segment in both plasmids which contains a 59-bp DNA sequence presumably involved in the acquisition of new genes by Tn21 and its relatives (Cameron et al. 1986). It is likely that the recombination occurs precisely at this point. At least one trans-acting function (an integrase) is required for the site-specific recombination. It has been localized to a 1456-bp BstEII-BamHI fragment of Tn21 and can efficiently complement the integration of plasmids containing the integration site.
IncW质粒R388以及包含Smr和Sur基因的Tn21 DNA区域能够进行不依赖RecA的重组。这种重组以相对较高的频率发生（每个受体分子产生高达10^(-4)个重组体），并导致两个质粒的整合。在此过程中未形成可检测到的重复序列。两个质粒中的交叉点已被限定在一个0.4 kb的同源区段内，该区段包含一个59 bp的DNA序列，推测该序列与Tn21及其相关元件获取新基因有关（Cameron等人，1986年）。重组很可能恰好发生在这一点。位点特异性重组至少需要一种反式作用功能（一种整合酶）。它已被定位到Tn21的一个1456 bp的BstEII - BamHI片段上，并且能够有效地补充含有整合位点的质粒的整合。
