Tavakoli N, Comanducci A, Dodd H M, Lett M C, Albiger B, Bennett P
Laboratoire de Microbiologie et de Génétique, UPRES A 7010-CNRS, 28, rue Goethe, Strasbourg Cedex, 67083, France.
Plasmid. 2000 Jul;44(1):66-84. doi: 10.1006/plas.1999.1460.
IS1294, found on the ColD-like resistance plasmid pUB2380, is IS91-like. It is an active 1.7-kb insertion sequence that lacks terminal inverted repeats, displays insertion-site specificity, and does not generate direct repeats of the target site. The element has one large open reading frame, tnp(1294), encoding a transposase of 351 amino acids, related to members of the REP family of replication proteins used by RC-plasmids of gram-positive bacteria. IS1294 transposes using rolling-circle replication, initiated at one end of the element, oriIS, and terminated at the other, terIS. oriIS and terIS are highly conserved among like IS elements. oriIS resembles the leading strand replication origins of RC-plasmids; terIS resembles a rho-independent transcription terminator. IS1294 mediates not only its own transposition, but also sequences adjacent to terIS. A transposition model for IS1294 and related elements, involving rolling-circle replication and single-strand DNA intermediates, is presented.
IS1294发现于类ColD抗性质粒pUB2380上，与IS91类似。它是一个活跃的1.7千碱基对插入序列，缺乏末端反向重复序列，具有插入位点特异性，且不会产生靶位点的直接重复序列。该元件有一个大的开放阅读框tnp(1294)，编码一个351个氨基酸的转座酶，与革兰氏阳性菌的RC质粒所使用的REP复制蛋白家族成员相关。IS1294通过滚环复制进行转座，从元件的一端oriIS起始，在另一端terIS终止。oriIS和terIS在类似的IS元件中高度保守。oriIS类似于RC质粒的前导链复制起点；terIS类似于一个不依赖ρ因子的转录终止子。IS1294不仅介导自身的转座，还介导terIS附近的序列。本文提出了一个IS1294及相关元件的转座模型，涉及滚环复制和单链DNA中间体。
