de la Cruz F, Grinsted J
J Bacteriol. 1982 Jul;151(1):222-28. doi: 10.1128/jb.151.1.222-228.1982.
Tge transposon Tn21 has been transposed from R100.1 to plasmid pACYC184 and, from the resulting recombinants, to plasmid R388. The sites of insertion and the orientation of the element in several pACYC184::Tn21 recombinants have been examined. Restriction enzyme analysis of these recombinants has resulted in a detailed map of Tn21; this is compared with the published maps of the relevant part of R100.1. Heteroduplex analysis has shown short inverted repeat sequences at the ends of the element. With various in vitro-generated deletion mutants of Tn21, the internal gene necessary for transposition (tnpA) was localized within the terminal 4.3 kilobases of the right-hand end of the element. Genetic analysis of transposition of Tn21 suggests that the process proceeds via cointegrates. Since the end products of transposition are simple recombinants of the element and the recipient replicon, Tn21 must contain a gene that codes for a resolvase type of activity (tnpR gene).
转座子Tn21已从R100.1转座到质粒pACYC184，并从所得重组体转座到质粒R388。已检测了几个pACYC184::Tn21重组体中元件的插入位点和方向。对这些重组体的限制性酶切分析得出了Tn21的详细图谱；将其与R100.1相关部分的已发表图谱进行了比较。异源双链分析显示元件末端存在短的反向重复序列。利用Tn21的各种体外产生的缺失突变体，转座所需的内部基因（tnpA）定位于元件右端末端的4.3千碱基内。Tn21转座的遗传分析表明该过程通过共整合体进行。由于转座的终产物是元件和受体复制子的简单重组体，Tn21必须包含一个编码解离酶活性类型的基因（tnpR基因）。
