Genetic diversity and evolutionary features of type VI secretion systems in Salmonella
Genetic diversity and evolutionary features of type VI secretion systems in Salmonella
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沙门氏菌VI型分泌系统的遗传多样性和进化特征
DOI：
10.2217/fmb-2018-0260
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发表时间：
2019-01-01
影响因子：
3.1
通讯作者：
Liu, Shu-Lin
中科院分区：
文献类型：
--
作者：
Bao, Hongxia;Zhao, Jian-Hua;Liu, Shu-Lin
目的：VI 型分泌系统 (T6SS) 在细菌发病机制中发挥关键作用，但其进化特征仍不清楚。在这项研究中，我们对沙门氏菌中记录的 T6SS 进行了系统比较，并确定了它们的结构多样性、系统发育分布和谱系特异性。材料和方法：我们通过隐马尔可夫模型筛选了 295 个沙门氏菌基因组中的 13 个 T6SS 核心成分，并鉴定了涵盖 i1、i2、i3 和 i4a 类型的 363 个 T6SS 簇。结果：i3 型和 i4a 型 T6SS 分别限于肠沙门氏菌肠亚种和邦戈里沙门氏菌。而i2型T6SSs在肠沙门氏菌亚种、亚利桑那州和双亚利桑那州之间是保守的。肠沙门氏菌亚种salamae、indica和houtenae仅含有i1型T6SS，分布范围广，序列多样性高。结论：不同的沙门氏菌 T6SS 在细菌进化过程中经历了纯化选择压力，并可能参与宿主适应。
Aim: Type VI secretion systems (T6SS) play key roles in bacterial pathogenesis, but their evolutionary features remain largely unclear. In this study, we conducted systematic comparisons among the documented T6SSs in Salmonella and determined their structural diversity, phylogenetic distribution and lineage-specific properties. Materials & methods: We screened 295 Salmonella genomes for 13 T6SS core components by hidden Markov models and identified 363 T6SS clusters covering types i1, i2, i3 and i4a. Results: Type i3 and i4a T6SSs were restricted to Salmonella enterica subspecies enterica and Salmonella bongori, respectively. whereas type i2 T6SSs were conserved between S. enterica subspecies, arizonae and diarizonae. S. enterica subspecies salamae, indica and houtenae harbored only type i1 T6SSs, which had wide distribution and high sequence diversity. Conclusion: The diverse Salmonella T6SSs have undergone purifying selection pressures during the bacterial evolution and may be involved in host adaptation.