Voellmy R W, Goldberg A L
Nature. 1981 Apr 2;290(5805):419-21. doi: 10.1038/290419a0.
Despite knowledge of the physiological significance and regulation of protein degradation in bacteria, the pathway of proteolysis and the responsible enzymes are still not known. Degradation of cell proteins in bacterial and animal cells requires continuous ATP production, inhibition of which in Escherichia coli prevents the degradation of normal proteins in growing cells, accelerated breakdown of such proteins in starving cultures and the very rapid breakdown of abnormal proteins. Intracellular proteolysis proceeds by repeated endoproteolytic steps and ATP is required for the initial cleavages of the substrate. We have recently demonstrated ATP stimulation of proteolysis in extracts of bacterial and animal cells. These ATP-stimulated systems seem to be responsible for the rapid degradation of abnormal proteins in vivo, but they may also be involved in the catabolism of normal cell proteins, limited proteolysis, such as the processing of precursors for secreted or membrane proteins, and the selective inactivation of specific proteins, as occurs in the ATP-dependent cleavage of the lambda repressor by the recA protein. We report here that membrane fragments contain an ATP-stimulated protease that degrades cell proteins to large peptides (of molecular weight (MW) 71,500) which are then rapidly hydrolysed to amino acids by soluble ATP-independent enzymes.
尽管人们已经了解细菌中蛋白质降解的生理意义和调控机制，但蛋白水解途径及相关酶仍不明确。细菌和动物细胞中细胞蛋白的降解需要持续产生ATP，在大肠杆菌中抑制ATP的产生会阻止生长细胞中正常蛋白质的降解，导致饥饿培养物中此类蛋白质的加速分解以及异常蛋白质的快速分解。细胞内蛋白水解通过反复的内切蛋白水解步骤进行，底物的初始切割需要ATP。我们最近证明了ATP对细菌和动物细胞提取物中蛋白水解的刺激作用。这些ATP刺激系统似乎负责体内异常蛋白质的快速降解，但它们也可能参与正常细胞蛋白质的分解代谢、有限的蛋白水解，如分泌蛋白或膜蛋白前体的加工，以及特定蛋白质的选择性失活，就像recA蛋白对λ阻遏物的ATP依赖性切割那样。我们在此报告，膜片段含有一种ATP刺激的蛋白酶，它将细胞蛋白降解为大肽（分子量为71,500），然后这些大肽会被可溶性的不依赖ATP的酶迅速水解为氨基酸。
