Distinct actions of cis and trans ATP within the double ring of the chaperonin GroEL
Distinct actions of cis and trans ATP within the double ring of the chaperonin GroEL
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DOI：
10.1038/42047
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发表时间：
1997-08-21
期刊：
影响因子：
64.8
通讯作者：
Horwich, AL
中科院分区：
文献类型：
--
作者：
Rye, HS;Burston, SG;Horwich, AL
伴侣蛋白GroEL是一种双环结构，在每个环中具有一个中心空腔，当在腺嘌呤核苷酸（4-8）的存在下被共伴侣蛋白GroES加帽时，其为蛋白质（1-3）的有效折叠提供了环境。在顺式三元复合物中观察到底物罗丹酸的有效折叠，其中GroES和多肽结合到由ATP、ADP或不可水解的ATP类似物形成的相同环上（2，9），表明对ATP的特定需求仅限于反式环中将GroES和多肽从顺式侧驱逐的作用（9）。然而，我们在这里表明，对于苹果酸脱氢酶和Rubisco的折叠，在顺式环中也绝对需要ATP，因为ADP和AMP-PNP不能促进折叠。我们研究了特定的作用，结合和水解ATP的顺式和反式环使用GroEL的突变形式，结合ATP，但在其水解有缺陷。ATP和GroES的顺式结合在高度稳定的GroEL-ATP-GroES复合物内引发生产性折叠。为了释放GroES和多肽，需要顺式环中的ATP水解以形成稳定性降低的GroEL-ADP-GroES复合物，引发顺式复合物通过反式环中的ATP结合（不水解）释放。这些观察结果解释了为什么GroEL作为双环复合物发挥作用。
The chaperonin GroEL is a double-ring structure with a central cavity in each ring that provides an environment for the efficient folding of proteins(1-3) when capped by the co-chaperone GroES in the presence of adenine nucleotides(4-8). Productive folding of the substrate rhodanese has been observed in cis ternary complexes, where GroES and polypeptide are bound to the same ring, formed with either ATP, ADP or non-hydrolysable ATP analogues(2,9), suggesting that the specific requirement for ATP is confined to an action in the trans ring that evicts GroES and polypeptide from the cis side(9). We show here, however, that for the folding of malate dehydrogenase and Rubisco there is also an absolute requirement for ATP in the cis ring, as ADP and AMP-PNP are unable to promote folding. We investigated the specific roles of binding and hydrolysis of ATP in the cis and trans rings using mutant forms of GroEL that bind ATP but are defective in its hydrolysis. Binding of ATP and GroES in cis initiated productive folding inside a highly stable GroEL-ATP-GroES complex. To discharge GroES and polypeptide, ATP hydrolysis in the cis ring was required to form a GroEL-ADP-GroES complex with decreased stability, priming the cis complex for release by ATP binding (without hydrolysis) in the trans ring. These observations offer an explanation of why GroEL functions as a double-ring complex.