Rogowsky P, Schmitt R
Mol Gen Genet. 1984;193(1):162-6. doi: 10.1007/BF00327431.
The related transposons Tn501 and Tn1721 have a 3.8 kb region in common that contains two genes (tnpA and tnpR) and a resolution site (res) required for transposition. Resolvase, the product of tnpR, catalyses site-specific recombination at res, a 186 base pair (bp) sequence located adjacent to tnpR at one end of the homology region. We describe here identification of the crossover site within res. It involved the construction of a plasmid containing copies of res (Tn501) and res (Tn1721) in direct orientation and tnpR-mediated intramolecular recombination between the two homologous (but non-identical) sites. The resulting hybrid contained Tn501 and Tn1721 fused at the crossover point. DNA sequence analysis of the recombinant indicates that recombination occurs in an 11 bp region of exact homology between Tn501 and Tn1721. The recombination site lies 161-172 bp upstream of tnpR at the transition from homology to non-homology between Tn501 and Tn1721 suggesting that site-specific recombination may have played a role in the evolution of these elements.
相关转座子Tn501和Tn1721有一个3.8 kb的共同区域，其中包含两个基因（tnpA和tnpR）以及转座所需的一个解离位点（res）。解离酶是tnpR的产物，它催化res位点特异性重组，res是一个186碱基对（bp）的序列，位于同源区域一端与tnpR相邻处。我们在此描述res内交叉位点的鉴定。这涉及构建一个质粒，该质粒包含同向排列的res（Tn501）和res（Tn1721）拷贝，以及tnpR介导的两个同源（但不相同）位点之间的分子内重组。产生的杂种在交叉点处含有融合的Tn501和Tn1721。对重组体的DNA序列分析表明，重组发生在Tn501和Tn1721之间11 bp的精确同源区域。重组位点位于Tn501和Tn1721从同源到非同源转变处tnpR上游161 - 172 bp处，这表明位点特异性重组可能在这些元件的进化中发挥了作用。
