Integrating conjugative elements of the SXT/R391 family trigger the excision and drive the mobilization of a new class of Vibrio genomic islands
Integrating conjugative elements of the SXT/R391 family trigger the excision and drive the mobilization of a new class of Vibrio genomic islands
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DOI：
10.1111/j.1365-2958.2010.07364.x
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发表时间：
2010-11-01
影响因子：
3.6
通讯作者：
Burrus, Vincent
中科院分区：
文献类型：
--
作者：
Daccord, Aurelie;Ceccarelli, Daniela;Burrus, Vincent
在弧菌和肠杆菌中，SXT/R391家族的接合元件（ICE）的整合常常促进横向基因转移。SXT/R391 ICE通过位点特异性重组整合到prfC中，并通过缀合转移，这是一个在称为转移起点（oriT（SXT））的特定基因座启动的过程。我们在三种弧菌中鉴定了含有与oriT（SXT）具有> 63%同一性的序列的基因组岛（GI）。与SXT/R391 ICE不同，这些GI被整合到编码推定的应激诱导蛋白的基因中，并且似乎不携带编码接合机制或动员蛋白的任何基因。我们的研究结果表明，SXT/R391 ICE触发切除和介导的接合转移在反式的三个弧菌GI在高频率。GI的切除不依赖于ICE编码的重组酶，并且由ICE编码的转录激活因子SetCD控制，SetCD在宿主SOS反应期间表达。mobI和traI是ICE携带的两个与oriT识别有关的基因，对GI的转移至关重要。我们还发现SXT/R391 ICE反式移动了位于GI整合位点5'的染色体DNA超过1 Mb。这些结果共同支持了通过SXT/R391家族的ICE动员GI的新机制。
P>In vibrios and enterobacteria lateral gene transfer is often facilitated by integrating conjugative elements (ICEs) of the SXT/R391 family. SXT/R391 ICEs integrate by site-specific recombination into prfC and transfer by conjugation, a process that is initiated at a specific locus called the origin of transfer (oriT(SXT)). We identified genomic islands (GIs) harbouring a sequence that shares > 63% identity with oriT(SXT) in three species of Vibrio. Unlike SXT/R391 ICEs, these GIs are integrated into a gene coding for a putative stress-induced protein and do not appear to carry any gene coding for a conjugative machinery or for mobilization proteins. Our results show that SXT/R391 ICEs trigger the excision and mediate the conjugative transfer in trans of the three Vibrio GIs at high frequency. GIs' excision is independent of the ICE-encoded recombinase and is controlled by the ICE-encoded transcriptional activator SetCD, which is expressed during the host SOS response. Both mobI and traI, two ICE-borne genes involved in oriT recognition, are essential for GIs' transfer. We also found that SXT/R391 ICEs mobilize in trans over 1 Mb of chromosomal DNA located 5' of the GIs' integration site. Together these results support a novel mechanism of mobilization of GIs by ICEs of the SXT/R391 family.