Zühlsdorf M T, Wiedemann B
Institut für Medizinische Mikrobiologie und Immunologie, University of Bonn, Germany.
J Gen Microbiol. 1993 May;139(5):995-1002. doi: 10.1099/00221287-139-5-995.
The Tn21 subgroup of class II transposons plays an important role in the dissemination of resistance genes and especially in the epidemic spread of multi-resistance. This ability reflects the variety of resistance genes that associate with the streptomycin/spectinomycin-resistance gene (aadA) of Tn21. Deletion experiments with Tn2426, a typical member of the Tn21 subgroup, and sequencing of the region that accommodates additional resistance genes revealed significant structural characteristics. Each resistance gene was flanked by short, directly repeated recombinationally active sequences with unexpected variability in their sequence and length. The consensus for a recombinationally active sequence appeared to be 13 bp in length (TAAAACAANGNNA), compared to previous estimates of 54 bp. This sequence, in combination with the product of the integrase gene, is responsible for the genetic variability of members of the Tn21 family of transposable elements and the dissemination of multi-resistance.
II类转座子的Tn21亚群在抗性基因的传播中，尤其是在多重抗性的流行传播中发挥着重要作用。这种能力反映了与Tn21的链霉素/壮观霉素抗性基因（aadA）相关的各种抗性基因。对Tn21亚群的典型成员Tn2426进行缺失实验，并对容纳额外抗性基因的区域进行测序，揭示了显著的结构特征。每个抗性基因两侧都有短的、直接重复的重组活性序列，其序列和长度具有意想不到的变异性。与之前估计的54 bp相比，重组活性序列的共有序列长度似乎为13 bp（TAAAACAANGNNA）。该序列与整合酶基因的产物共同作用，导致了转座元件Tn21家族成员的遗传变异性和多重抗性的传播。
