THE PRODUCT OF THE LON (CAPR) GENE IN ESCHERICHIA-COLI IS THE ATP-DEPENDENT PROTEASE, PROTEASE LA
THE PRODUCT OF THE LON (CAPR) GENE IN ESCHERICHIA-COLI IS THE ATP-DEPENDENT PROTEASE, PROTEASE LA
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DOI：
10.1073/pnas.78.8.4931
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
GOLDBERG, AL
中科院分区：
文献类型：
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作者：
CHUNG, CH;GOLDBERG, AL
在大肠在大肠杆菌中，异常蛋白质的降解是一个需要能量的过程;在lon（capR或deg）基因突变体中降解减少。lon基因编码的蛋白质是一种ATP依赖性蛋白酶，与最近在E.杆菌这两种蛋白质都是丝氨酸蛋白酶，在ATP和Mg 2+存在下水解酪蛋白和球蛋白，但不水解胰岛素。两者都对ATP有反应，但对其他核苷三磷酸反应不太好，对不可水解的ATP类似物也没有反应。纯化的lon蛋白具有450，000的表观分子量，似乎由4个相同的亚基组成。它的大小，色谱行为，对各种抑制剂和热的敏感性与蛋白酶La的相似。在一个携带lon+亲本菌株的额外拷贝的菌株中。携带无义突变capR 9和capR-的菌株也含有这种ATP依赖性蛋白水解活性，但其存在量明显较低，并且与野生型酶不同，可通过磷酸纤维素色谱法灭活。这些离子型菌株中异常蛋白质的降解比野生型慢，但仍需要ATP。lon突变体中ATP依赖性蛋白酶的改变可以解释细胞内蛋白水解的缺陷，也可能解释该多效性基因的其他表型效应。
In E. coli, degradation of abnormal proteins is an energy-requiring process; it is decreased in mutants in the lon (capR or deg) gene. The protein encoded by the lon gene is an ATP-dependent protease and is identical to protease La, recently described in E. coli. Both proteins are serine proteases that hydrolyze casein and globin, but not insulin, in the presence of ATP and Mg2+. Both respond to ATP, less well to other nucleoside triphosphates, and not to nonhydrolyzable ATP analogs. The purified lon protein has an apparent MW of 450,000 and appears to be composed of 4 identical subunits. Its size, chromatographic behavior, and sensitivity to various inhibitors and heat are indistinguishable from those of protease La. In a strain that carries additional copies of the lon+ parent strain. Strains carrying the nonsense mutations capR9 and capR- also contain this ATP-dependent proteolytic activity, but it is present in substantially lower amounts and is inactivated by phosphocellulose chromatography, unlike the wild-type enzyme. Degradation of abnormal proteins in these lon- strains, which is slower than in the wild type, still requires ATP. Alterations in the ATP-dependent protease in the lon- mutants can account for the defect in intracellular proteolysis and perhaps also for the other phenotypic effects of this pleiotropic gene.