INTEGRONS - NOVEL DNA ELEMENTS WHICH CAPTURE GENES BY SITE-SPECIFIC RECOMBINATION
INTEGRONS - NOVEL DNA ELEMENTS WHICH CAPTURE GENES BY SITE-SPECIFIC RECOMBINATION
复制标题
DOI：
10.1007/bf01435034
复制
发表时间：
1993-01-01
期刊：
影响因子：
1.5
通讯作者：
STOKES, HW
中科院分区：
文献类型：
--
作者：
HALL, RM;STOKES, HW
整合子是不常见的DNA元件，其包括编码位点特异性DNA重组酶的基因、DNA整合酶和邻近位点，在所述邻近位点处发现多种抗生素抗性和其它基因作为插入物。在插入区域中可以发现一个或多个基因，但是每个基因是独立基因盒的一部分。插入的基因从位于基因5'端的保守序列中的启动子表达，因此整合子是天然表达载体。已经提出并实验验证了一种基因插入模型，其中环状基因盒通过单个位点特异性重组事件单独插入。基因盒包括基因编码区和在基因3'端的不完全反向重复序列，即59个碱基的元件。59-碱基元件是作为DNA整合酶识别位点起作用的元件的多样性家族。因此，单个基因的位点特异性插入代表了有助于革兰氏阴性菌基因组及其质粒和转座子进化的进一步机制。研究最多的一类整合子的成员，包括保守序列中的sull基因，被认为是移动的DNA元件，这是基于它们在许多独立的位置被发现，并且在5 ′-保守片段的外端发现离散边界。然而，在迄今为止检查的整合子中，3 '保守片段的长度是可变的，并且这种可变性可能是由于插入和缺失事件而出现的。虽然3 '保守片段的真实范围仍有待确定，但这些整合子似乎很可能是移动的DNA元件。第二类已知的整合子包括Tn 7转座子家族的成员。
Integrons are unusual DNA elements which include a gene encoding a site-specific DNA recombinase, a DNA integrase, and an adjacent site at which a wide variety of antibiotic resistance and other genes are found as inserts. One or more genes can be found in the insert region, but each gene is part of an independent gene cassette. The inserted genes are expressed from a promoter in the conserved sequences located 5' to the genes, and integrons are thus natural expression vectors. A model for gene insertion in which circular gene cassettes are inserted individually via a single site-specific recombination event has been proposed and verified experimentally. The gene cassettes include a gene coding region and, at the 3' end of the gene an imperfect inverted repeat, a 59-base element. The 59-base elements are a diverse family of elements which function as sites recognized by the DNA integrase. Site-specific insertion of individual genes thus represents a further mechanism which contributes to the evolution of the genomes of Gram-negative bacteria and their plasmids and transposons.Members of the most studied class of integrons, which include the sull gene in the conserved sequences, are believed to be mobile DNA elements on the basis that they are found in many independent locations, and a discrete boundary is found at the outer end of the 5'-conserved segment. However, the length of the 3'-conserved segment is variable in the integrons examined to date, and it is likely that this variability has arisen as the result of insertion and deletion events. Though the true extent of the 3'-conserved segment remains to be determined, it seems likely that these integrons are mobile DNA elements. The second known class of integrons comprises members of the Tn7 transposon family.