细菌体内的蛋白质降解

Proteolysis in bacteria-A review

为了适应多变的外界环境,细菌利用蛋白降解来清除体内不需要的蛋白质。AAA+蛋白酶降解机制在细菌蛋白质质量控制系统中发挥重要作用,而在放线菌中发现的蛋白酶体揭示了原核生物体内一个崭新的蛋白质降解机制。蛋白酶只识别携带降解决定子的底物,确保了蛋白质降解的特异性,除此之外细菌还通过一些其他方式调控蛋白质的降解与否。随着真核生物体内泛素依赖的蛋白酶体降解途径的发现,蛋白质降解过程参与调控机体生理活动的功能也逐渐为人所知。研究发现,蛋白质降解参与调控细菌的生长、分化,并与细菌的应激反应以及毒力等相关。本文将对细菌中存在的AAA+蛋白质降解机制,包括其结构、对底物的降解过程及其生理功能等进行阐述。

To adapt quickly to the environmental change, bacteria have evolved a protein quality control （PQC） network to remove unwanted proteins. AAA ＋ （ATPases associated with diverse cellular activities） proteases form a major part of this PQC network, and the discovery of Pup （prokaryotie ubiquitin-like protein ）-proteasome system revealed a novel mechanism of prokaryotic protein degradation. Proteolytic machines only degrade substrates bearing a degradation tag or degron to insure the proteolysis specificity. In addition, bacteria adopt different strategies to regulate the protein degradation. With the discovery of Ubiquitin-mediated protein degradation in eukaryotes, it has become evident that regulated protein degradation plays a crucial role in the cell response to environment change among eukaryotes and prokaryotes. Regulation by proteolysis has been shown to be involved in diverse bacterial cellular processes including growth, division, differentiation, pathogenesis and stress response. This review will focus on the structure, degradation process, and the function of AAA ＋ proteolytic machines in bacteria.