The Hsp70 Ssz1 modulates the function of the ribosome-associated J-protein Zuo1
The Hsp70 Ssz1 modulates the function of the ribosome-associated J-protein Zuo1
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DOI：
10.1038/nsmb942
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发表时间：
2005-06-01
影响因子：
16.8
通讯作者：
Craig, EA
中科院分区：
文献类型：
--
作者：
Huang, P;Gautschi, M;Craig, EA
J蛋白是Hsp 70的专性伴侣，形成了一类普遍存在的分子伴侣机制。酵母Ssb的核糖体相关Hsp 70在新生多肽离开核糖体时结合新生多肽。在这里，我们报告说，核糖体相关的J-蛋白Zuo 1的合作伙伴的Ssb。然而，Zuo 1有效地刺激ATP酶活性的Ssb只有在复杂的另一个热休克蛋白70，Ssz 1。Ssz 1结合ATP，但没有11个不同的氨基酸取代的ATP结合裂缝影响Ssz 1在体内的功能，这表明既不需要核苷酸结合，也不需要水解。我们建议，Ssz 1在细胞中的主要功能是促进Zuo 1作为核糖体上Ssb的J-蛋白伴侣发挥作用的能力，作为Hsp 70家族成员的一个例子，该家族成员已经进化到执行不同于伴侣的功能。
J-proteins are obligate partners of Hsp70s, forming a ubiquitous class of molecular chaperone machinery. The ribosome-associated Hsp70 of yeast Ssb binds nascent polypeptides as they exit the ribosome. Here we report that the ribosome-associated J-protein Zuo1 is the partner of Ssb. However, Zuo1 efficiently stimulates the ATPase activity of Ssb only when in complex with another Hsp70, Ssz1. Ssz1 binds ATP, but none of the 11 different amino acid substitutions in the ATP-binding cleft affected Ssz1 function in vivo, suggesting that neither nucleotide binding nor hydrolysis is required. We propose that Ssz1's predominant function in the cell is to facilitate Zuo1's ability to function as a J-protein partner of Ssb on the ribosome, serving as an example of an Hsp70 family member that has evolved to carry out functions distinct from that of a chaperone.