Identification and characterization of int (integrase), xis (excisionase) and chromosomal attachment sites of the integrative and conjugative element ICEBs1 of Bacillus subtilis
Identification and characterization of int (integrase), xis (excisionase) and chromosomal attachment sites of the integrative and conjugative element ICEBs1 of Bacillus subtilis
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DOI：
10.1111/j.1365-2958.2007.06000.x
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发表时间：
2007-12-01
影响因子：
3.6
通讯作者：
Grossman, Alan D.
中科院分区：
文献类型：
--
作者：
Lee, Catherine A.;Auchtung, Jennifer M.;Grossman, Alan D.
ICEBs1是枯草芽孢杆菌中整合的共轭元件（共轭转座子）。作为对DNA损伤或潜在交配对象高浓度的反应，ICEBs1可以切除并转移到包括其他物种在内的各种受体。我们发现，ICEBs1的切除发生在标记ICEBs1与染色体DNA连接的60 bp直接重复序列内的位点特异性重组。切除需要两个ICEBs1基因，int（整合酶，ydcL），预计编码类似于噬菌体lambda的酪氨酸重组酶和xis（切除酶，sacV）。xis的异位表达足以诱导ICEBs1的切除，这表明DNA损伤和肽信号对xis转录的调节通常控制着切除。特定于站点的集成需要Int，而不需要Xis。我们发现，在trnS-leu2中缺乏初级细菌附着位点（attB）的情况下，ICEBs1整合在二级附着位点上，类似于attB中17bp的序列。在缺乏int的情况下，只要ICEBs1含有与染色体位点序列相同的区域，就可以通过依赖reca的同源重组重组到染色体中。
ICEBs1 is an integrative and conjugative element (conjugative transposon) integrated into trnS-leu2 in Bacillus subtilis. In response to DNA damage or high concentrations of potential mating partners, ICEBs1 can excise and transfer to various recipients, including other species. We found that excision of ICEBs1 occurs by site-specific recombination within 60 bp direct repeats that mark the junctions between ICEBs1 and chromosomal DNA. Excision required two ICEBs1 genes, int (integrase, ydcL), predicted to encode a tyrosine recombinase similar to that of phage lambda, and xis (excisionase, sacV). Ectopic expression of xis was sufficient to induce excision of ICEBs1, indicating that regulation of xis transcription by DNA damage and peptide signalling normally controls excision. Int, but not Xis, was needed for site-specific integration. We found that in the absence of the primary bacterial attachment site (attB) in trnS-leu2, ICEBs1 integrated in secondary attachment sites that are similar to a 17 bp sequence in attB. In the absence of int, ICEBs1 could recombine into the chromosome by RecA-dependent homologous recombination, provided ICEBs1 contained a region of sequence identity to a chromosomal locus.