Schöffl F, Arnold W, Pühler A, Altenbuchner J, Schmitt R
Mol Gen Genet. 1981;181(1):87-94. doi: 10.1007/BF00339010.
The 10.7 kilobase (kb) tetracycline resistance transposons Tn1721 and Tn1771, isolated from disparate sources, are completely homologous on the basis of heteroduplex analyses. Both transposable elements are capable of forming multiple duplications of a 5.3 kb portion encompassing the resistance genes (tet region). A model accounting for both, recA-independent translocation and recA-dependent amplification, postulates two direct and one inverted repeat as essential constituents of the transposons. DNA sequence analyses of Tn1721 and Tn1771 have substantiated this model. They demonstrated three identical 38 base pair repeats identically in both transposons dividing them into a "minor transposon" and a tet region. Identical sequences of at least 87 base pairs providing recombination "hot spots" for gene duplication have been found at the ends of the repetitious tet region. Translocation of Tn1721 and Tn1771 generates five base pair direct repeats at the respective sites of insertion. On the basis of the heteroduplex molecules and sequences analyzed the two transposons are identical.
从不同来源分离得到的10.7千碱基（kb）四环素抗性转座子Tn1721和Tn1771，基于异源双链分析完全同源。这两种转座元件都能够形成包含抗性基因（tet区域）的5.3 kb部分的多个重复序列。一个解释recA非依赖性易位和recA依赖性扩增的模型假定两个正向重复序列和一个反向重复序列是转座子的基本组成部分。Tn1721和Tn1771的DNA序列分析证实了该模型。它们在两个转座子中都显示出三个相同的38碱基对重复序列，将它们分为一个“小转座子”和一个tet区域。在重复的tet区域末端发现了至少87碱基对的相同序列，为基因重复提供重组“热点”。Tn1721和Tn1771的易位在各自的插入位点产生五个碱基对的正向重复序列。基于分析的异源双链分子和序列，这两个转座子是相同的。
