Salyers A A, Shoemaker N B, Stevens A M, Li L Y
Department of Microbiology, University of Illinois, Urbana 61801, USA.
Microbiol Rev. 1995 Dec;59(4):579-90. doi: 10.1128/mr.59.4.579-590.1995.
Conjugative transposons are integrated DNA elements that excise themselves to form a covalently closed circular intermediate. This circular intermediate can either reintegrate in the same cell (intracellular transposition) or transfer by conjugation to a recipient and integrate into the recipient's genome (intercellular transposition). Conjugative transposons were first found in gram-positive cocci but are now known to be present in a variety of gram-positive and gram-negative bacteria also. Conjugative transposons have a surprisingly broad host range, and they probably contribute as much as plasmids to the spread of antibiotic resistance genes in some genera of disease-causing bacteria. Resistance genes need not be carried on the conjugative transposon to be transferred. Many conjugative transposons can mobilize coresident plasmids, and the Bacteroides conjugative transposons can even excise and mobilize unlinked integrated elements. The Bacteroides conjugative transposons are also unusual in that their transfer activities are regulated by tetracycline via a complex regulatory network.
接合转座子是整合的DNA元件，它们可自我切除形成共价闭合的环状中间体。这个环状中间体既可以在同一细胞内重新整合（细胞内转座），也可以通过接合转移到受体细胞并整合到受体基因组中（细胞间转座）。接合转座子最初在革兰氏阳性球菌中发现，但现在已知也存在于多种革兰氏阳性和革兰氏阴性细菌中。接合转座子具有惊人的广泛宿主范围，在某些致病细菌属中，它们对抗生素抗性基因传播的作用可能与质粒一样大。抗性基因不一定携带在接合转座子上才能被转移。许多接合转座子可以动员共存的质粒，而拟杆菌属的接合转座子甚至可以切除并动员不相连的整合元件。拟杆菌属的接合转座子也很特别，因为它们的转移活性受四环素通过复杂的调控网络调控。
