细菌插入序列中的转座酶和转座机制

Transposases in Bacterial Insertion Sequencesand Their Transposition Mechanisms

插入序列(insertion sequence, IS)是细菌中最简单的移动遗传因子,由两端的反向重复序列(inverted repeats, IR)和中间的转座酶(transposase)编码序列组成。在细菌中,因为插入序列的转座酶催化活性中心氨基酸序列不同,所以将其转座酶分为DDE转座酶、DEDD转座酶、HUH转座酶和丝氨酸转座酶。在转座过程中,根据插入序列是否有复制,将插入序列的转座分为复制型转座(replicative transposition)和非复制型转座(non-replicative transposition),而将形成夏皮罗中间体(Shapiro intermediate)的非复制型转座称为保守型转座(conservative transposition)。此外,插入序列通过不同的转座机制插入到基因编码区导致基因突变、缺失和倒置;或者插入到基因上游,通过自身启动子或与基因形成杂交启动子来影响插入序列下游基因的表达,从而帮助细菌抵抗复杂的环境变化。本文主要围绕细菌插入序列的特征、转座酶、转座机制和转座影响展开综述,以期为进一步研究插入序列的机制和插入序列在细菌中所起的作用提供参考。

The insertion sequence （IS） is the simplest mobile genetic element consisting of inverted repeats （IRs） and transposase coding sequences. In bacteria, the transposase is divided into DDE, DEDD, HUH and serine transposases, categorized by the different amino acid sequences at the catalytic activity center. The transposition is divided into replicative and non-replicative transposition, depending upon whether IS is replicated. Furthermore, non-replicative transposition that produces the Shapiro intermediate is termed conservative transposition. As a result of transposition, IS is inserted into the gene coding region, leading to gene mutation, deletion and inversion. Alternatively, IS can be inserted into the upstream region of a gene to influence its transcription and expression via the IS own promoter or the hybridization promoter, so as to help bacteria resist complex environmental chanzes. This review mainlv focuses on bacterial IS, the transposases, the transposition and the effects of transposition, in order to provide a reference for further studying the mechanism of IS and the functional role of IS in bacteria.