Glycine-alanine repeats impair proper substrate unfolding by the proteasome
Glycine-alanine repeats impair proper substrate unfolding by the proteasome
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DOI：
10.1038/sj.emboj.7601058
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发表时间：
2006-04-19
期刊：
影响因子：
11.4
通讯作者：
Coffino, Philip
中科院分区：
文献类型：
--
作者：
Hoyt, Martin A.;Zich, Judith;Coffino, Philip
蛋白酶体atp酶解开折叠的蛋白质。将只含有甘氨酸和丙氨酸残基（GAr）的序列引入底物会损害底物的消化。我们之前提出GAr干扰蛋白酶体的展开能力，导致产物的部分降解。在这里，我们用几种方法测试了这个想法。稳定或破坏底物蛋白内折叠结构域改变了模型预测的gar介导的中间体生产方式。下游折叠结构域决定了末端蛋白水解的位点。GAr和折叠结构域之间的间距对于中间产物的产生至关重要。含有GAr的中间体不与蛋白酶体保持关联，排除了保留含有GAr的蛋白质停止进一步加工的模型。支持以下模型：位于atp酶环内的GAr降低了核苷酸水解和在底物上进行的功之间的耦合效率。如果这种损伤发生在必须启动展开时，插入暂停，蛋白质水解仅限于已经进入蛋白酶体催化室的底物部分。
Proteasome ATPases unravel folded proteins. Introducing a sequence containing only glycine and alanine residues (GAr) into substrates can impair their digestion. We previously proposed that a GAr interferes with the unfolding capacity of the proteasome, leading to partial degradation of products. Here we tested that idea in several ways. Stabilizing or destabilizing a folded domain within substrate proteins changed GAr-mediated intermediate production in the way predicted by the model. A downstream folded domain determined the sites of terminal proteolysis. The spacing between a GAr and a folded domain was critical for intermediate production. Intermediates containing a GAr did not remain associated with proteasomes, excluding models whereby retained GAr-containing proteins halt further processing. The following model is supported: a GAr positioned within the ATPase ring reduces the efficiency of coupling between nucleotide hydrolysis and work performed on the substrate. If this impairment takes place when unfolding must be initiated, insertion pauses and proteolysis is limited to the portion of the substrate that has already entered the catalytic chamber of the proteasome.