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.

沙门氏菌基因组岛 1 (SGI1) 是一种整合可移动元件 (IME)，20 年前首次在多重耐药鼠伤寒沙门氏菌 DT104 克隆中报道。自第一次报告以来，在肠道沙门氏菌和奇异变形杆菌中发现了许多变体和亲属。由于全基因组测序，最近几年在 Gammaproteobacteria 中报道了越来越多的 SGI1 相关元件 (SGI1-RE) 的完整序列。在这里，总结了 SGI1-RE 共有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，靶向trmE的 3'-末端基因。它们共享相同的遗传组织（整合酶和切除酶基因、复制酶模块、SgaCD 样转录激活基因、traN、traG、mpsB/mpsA基因），并且它们具有 AcaCD 结合位点，可在 A/C 存在下促进它们的切除、复制和动员质粒。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抗性 (MAR) 区域，其 MAR 区域的可塑性表明 SGI1-RE 在抗生素抗性中发挥关键作用，并可能帮助多重抗生素抗性细菌适应其环境。这或许可以解释 SGI1-RE 克隆的出现。