Ⅳ型分泌系统及其对细菌重金属抗性的影响

Roles of the type IV secretion systems in bacterial resistance to heavy metals

Ⅳ型分泌系统(typeⅣsecretion system,T4SS)是广泛存在于细菌中的特殊蛋白分泌系统,不同于其他分泌系统,该系统不仅能够转运蛋白质,还能转移DNA、DNA-蛋白质复合物。因此,T4SS具有多种生物学特性。T4SS能介导细菌的接合作用,而接合是水平基因转移(horizontal gene transfer,HGT)的重要机制之一,细菌能够利用T4SS介导的接合作用转移大部分可移动基因元件(mobile genetic element,MGE),如接合型质粒和整合性元件,从而使细菌获得新的基因,这些辅助基因在特定环境条件下有益于帮助细菌获得新功能,有助于细菌在新环境中占据生态位,极大地促进了细菌对环境条件变化的适应性。本文主要对细菌T4SS的生物学作用研究进展进行综述,并探讨了T4SS在细菌适应重金属环境中的作用。

The type IV secretion systems(T4SSs)are ubiquitous and versatile in bacteria,capable of transporting proteins,DNA,and protein-DNA complexes.Bacterial conjugation is a key mechanism of horizontal gene transfer.T4SSs can mediate the transfer of conjugative plasmids or integrative elements from one bacterium to another,which endow bacteria with new genes and functions.The acquisition of genes in this way not only enables bacteria to gain new functions but also helps them occupy niches,promoting the adaptation of bacteria to a new or changing environment.This article summarizes the roles of T4SSs,especially in bacterial adaptation to heavy metal-polluted environments.