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Abstract：
Salmonella genomic island 1 (SGI1), an integrative mobilisable element (IME), was first reported 20 years ago, in the multidrug resistant Salmonella Typhimurium DT104 clone. Since this first report, many variants and relatives have been found in Salmonella enterica and Proteus mirabilis. Thanks to whole genome sequencing, more and more complete sequences of SGI1-related elements (SGI1-REs) have been reported in these last few years among Gammaproteobacteria. Here, the genetic organisation and main features common to SGI1-REs are summarised to help to classify them. Their integrases belong to the tyrosine-recombinase family and target the 3\'-end of the trmE gene. They share the same genetic organisation (integrase and excisionase genes, replicase module, SgaCD-like transcriptional activator genes, traN, traG, mpsB/mpsA genes) and they harbour AcaCD binding sites promoting their excision, replication and mobilisation in presence of A/C plasmid. SGI1-REs are mosaic structures suggesting that recombination events occurred between them. Most of them harbour a multiple antibiotic resistance (MAR) region and the plasticity of their MAR region show that SGI1-REs play a key role in antibiotic resistance and might help multiple antibiotic resistant bacteria to adapt to their environment. This might explain the emergence of clones with SGI1-REs.
摘要：
沙门氏菌基因组岛1（SGI1），综合可移动元件(IME)，是20年前首次报道的，在多重耐药鼠伤寒沙门氏菌DT104克隆中。自从第一次报告以来，在肠沙门氏菌和奇异变形杆菌中发现了许多变体和亲戚。多亏了全基因组测序，在过去的几年中，已经报道了越来越多的SGI1相关元件（SGI1-REs）的完整序列。这里,总结了SGI1-REs常见的遗传组织和主要特征，以帮助对其进行分类。它们的整合酶属于酪氨酸重组酶家族，并靶向trmE基因的3'端。它们具有相同的遗传组织（整合酶和切除酶基因，复制酶模块，SgaCD样转录激活因子基因，traN,traG,mpsB/mpsA基因），并且它们带有促进其切除的AcaCD结合位点，在A/C质粒存在下的复制和动员。SGI1-RE是镶嵌结构，表明它们之间发生了重组事件。它们中的大多数具有多重抗生素耐药性（MAR）区域，其MAR区域的可塑性表明SGI1-REs在抗生素耐药性中起关键作用，并可能有助于多种抗生素耐药细菌适应环境。这可以解释具有SGI1-RE的克隆的出现。
