原核生物的NHEJ修复途径

Non-homologous End Joining Pathway in Prokaryotic Cells

DNA双链断裂(DSBs)是严重的DNA损伤形式之一,生物体对DSBs的修复可通过同源重组(HR)或非同源末端连接途径(NHEJ)进行。长期以来,人们普遍认为HR是细菌DSBs修复的惟一途径,但在分支杆菌和其它原核生物体内NHEJ途径的发现,使这一观念得以颠覆。最近的研究表明,细菌NHEJ修复系统是一个双组分系统,包含一个多功能的DNA连接酶(LigD)和DNA末端结合蛋白Ku,具有DSBs修复所需的断裂末段识别、末端加工和连接活性。重点综述细菌NHEJ修复系统的组成、结构以及生理功能。

DNA double strand breaks are one of the most lethal forms of DNA damage. Two major pathways,homologous recombi- nation（HR） and non-homologous end joining（NHEJ） ,have evolved to repair DSBs. It has been considered for a long time that HR is the only pathway for DSBs repair in bacteria. However,this notion has been overturned by the discovery of NHEJ in mycobacteria and other prokaryotic organisms. Recent studies have proved that bacterial NHEJ complex is a two-component system,containing a multi- functional DNA ligase（LigD） and DNA terminal binding protein Ku,which possess all of the end-recognizing, processing, gap-filling and ligation activities required for DSBs repair. The recent discoveries on the structure and physiological functions of bacterial NHEJ apparatus were reviewed briefly.