REGULATION OF 70-KDA HEAT-SHOCK-PROTEIN ATPASE ACTIVITY AND SUBSTRATE-BINDING BY HUMAN DNAJ-LIKE PROTEINS, HSJ1A AND HSJ1B
REGULATION OF 70-KDA HEAT-SHOCK-PROTEIN ATPASE ACTIVITY AND SUBSTRATE-BINDING BY HUMAN DNAJ-LIKE PROTEINS, HSJ1A AND HSJ1B
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DOI：
10.1111/j.1432-1033.1994.tb20030.x
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发表时间：
1994-11-15
期刊：
影响因子：
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通讯作者：
ANDERTON, BH
中科院分区：
文献类型：
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作者：
CHEETHAM, ME;JACKSON, AP;ANDERTON, BH
分子伴侣的DnaJ家族的特征在于存在高度保守的70个氨基酸的J结构域。大肠杆菌DnaJ与70-kDa热休克蛋白（DnaK）相互作用，在体外，刺激70-kDa热休克蛋白ATP酶活性和修改底物结合。DnaJ样蛋白与70-kDa热休克蛋白相互作用的保守性已在酵母蛋白YDJ 1中得到证实，YDJ 1是一种与大肠杆菌显示完全结构域保守性的蛋白。coli DnaJ.人类神经元特异性Dual-like蛋白HSJ 1a和HSJ 1b具有与大肠杆菌相同的J结构域和富含甘氨酸/苯丙氨酸的区域。coliDnaJ，尽管总的氨基酸同一性小于23%。我们已经调查，在体外，HSJ 1a和HSJ 1b与哺乳动物脑组成的70 kDa的热休克蛋白（hsc 70）的相互作用。弱的固有ATP酶活性的组成70 kDa的热休克蛋白增强超过5倍的化学计量量的HSJ 1a和HSJ 1b。这种增强是介导的结合ATP的水解率的增加，而ADP的释放率是不受影响的。HSJ 1蛋白似乎调节的70 kDa的组成型热休克蛋白的永久展开的底物，羧甲基化α-乳白蛋白的亲和力。最近的一份报告[Palleros，D. R.，Reid，K. L.，Shi，L.，美国，Welch，W. J. & Fink，A. L.（1993）Nature 365，664-666]已经提出，70-kDa热休克蛋白的底物释放需要由K+诱导的这些蛋白的构象变化与ATP结合一致。在ATP存在下，HSJ 1蛋白在Kf存在和不存在下都减少70-kDa组成型热休克蛋白/羧甲基化α-乳白蛋白复合物的形成，这表明HSJ 1蛋白诱导70-kDa组成型热休克蛋白的构象变化，其可以模拟K+介导的效应，因此调节70-kDa热休克蛋白。通过另一种机制释放休克蛋白底物，而不仅仅是刺激70-kDa热休克蛋白ATP酶活性。由于HSJ 1蛋白与DnaJ的相似性有限，我们认为这种作用是由J结构域单独介导的，并且这种对70 kDa热休克蛋白底物结合的调节对所有含有J结构域的蛋白质都是共同的。
The DnaJ family of molecular chaperones is characterized by the presence of a highly conserved 70-amino-acid J domain. Escherichia coli DnaJ interacts with the 70-kDa heat-shock protein (DnaK), in vitro, to stimulate the 70-kDa heat-shock protein ATPase activity and modify substrate binding. The conservation of the interaction of DnaJ-like proteins with the 70-kDa heat-shock proteins has been demonstrated for the yeast protein YDJ1, a protein that shows full domain conservation with E. coli DnaJ. Human neurone-specific Dual-like proteins, HSJ1a and HSJ1b, possess a J domain and a glycine/phenylalanine-rich region in common with E. coli DnaJ, although the overall amino acid identity is less than 23%. We have investigated, in vitro, the interaction of HSJ1a and HSJ1b with the mammalian brain constitutive 70-kDa heat-shock protein (hsc70). The weak intrinsic ATPase activity of the constitutive 70-kDa heat-shock protein is enhanced more than fivefold by stoichiometric amounts of both HSJ1a and HSJ1b. This enhancement is mediated by an increase in the rate of bound ATP hydrolysis, whereas the rate of ADP release is unaffected.HSJ1 proteins appear to regulate the affinity of the 70-kDa constitutive heat-shock protein for the permanently unfolded substrate, carboxymethylated alpha-lactalbumin. A recent report [Palleros, D. R., Reid, K. L., Shi, L., Welch, W. J. & Fink, A. L. (1993) Nature 365, 664-666] has suggested that substrate release by 70-kDa heat-shock proteins requires a conformational change in these proteins induced by K+ in concert with ATP binding. In the presence of ATP, HSJ1 proteins reduce 70-kDa constitutive heat-shock protein/carboxymethylated alpha-lactalbumin complex formation both in the presence and absence of Kf, This suggests that HSJ1 proteins induce a conformational change in the 70-kDa constitutive heat-shock protein that can mimic the effect mediated by K+ and therefore modulate 70-kDa heat-shock protein substrate release by another mechanism rather than merely stimulating the 70-kDa heat-shock protein ATPase activity. As HSJ1 proteins have limited similarity to DnaJ, we suggest that this action is being mediated by the J domain alone, and that this modulation of 70-kDa heat-shock-protein substrate binding will be common to all proteins that contain a J domain.