Identification and characterization of HsIV HsIU (ClpQ ClpY) proteins involved in overall proteolysis of misfolded proteins in Escherichia coli
Identification and characterization of HsIV HsIU (ClpQ ClpY) proteins involved in overall proteolysis of misfolded proteins in Escherichia coli
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DOI：
10.1002/j.1460-2075.1996.tb01082.x
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发表时间：
1996-12-16
期刊：
影响因子：
11.4
通讯作者：
Raina, S
中科院分区：
文献类型：
--
作者：
Missiakas, D;Schwager, F;Raina, S
大肠杆菌的热休克反应是自动调节的，与此一致，某些热休克基因的突变，如dna K，dna J，grpe或htrC的突变导致低温下结构性热休克基因的表达增加。类似的情况发生在由嘌呤霉素从核糖体中过早释放的新合成的多肽的积累上。我们寻找了这样的基因(S)，当它以多拷贝形式存在时，防止与htrC突变细菌相关的结构性热休克反应或由puromycin的存在引起的结构性热休克反应，其中一个这样的基因被鉴定并携带最近测序的hslV hslU(Clpq Clpy)操纵子，hslV/clpq与β亚基的成员有很高的同源性构成了20S蛋白酶体的催化核心。HslU/ClpY与大肠杆菌的ClpX蛋白有50%的同源性，已知ClpX蛋白向其伴侣--不依赖于ATP的蛋白水解酶ClpP递送大的多肽。我们发现，在体内，HslV和HslU相互作用并参与异常的嘌呤多肽的降解。生化证据表明，HslV/ClpQ是一种高效的多肽酶，在有ATP存在的情况下，HslU/ClpY可以增强其活性。
Heat shock response in Escherichia coli is autoregulated, Consistent with this, mutations in certain heat shock genes, such as dnaK, dnaJ, grpE or htrC lead to a higher constitutive heat shock gene expression at low temperatures, A similar situation occurs upon accumulation of newly synthesized peptides released prematurely from the ribosomes by puromycin, We looked for gene(s) which, when present in multicopy, prevent the constitutive heat shock response associated with htrC mutant bacteria or caused by the presence of puromycin, One such locus was identified and shown to carry the recently sequenced hslV hslU (clpQ clpY) operon, HslV/ClpQ shares a very high degree of homology with members of the beta-type subunit, constituting the catalytic core of the 20S proteasome. HslU/ClpY is 50% identical to the ClpX protein of E.coli, which is known to present large polypeptides to its partner, the ATP-independent proteolytic enzyme ClpP, We show that, in vivo, HslV and HslU interact and participate in the degradation of abnormal puromycylpolypeptides. Biochemical evidence suggests that HslV/ClpQ is an efficient peptidase whose activity is enhanced by HslU/ClpY in the presence of ATP.