A Conserved Unfoldase Activity for the p97 AAA-ATPase in Proteasomal Degradation
A Conserved Unfoldase Activity for the p97 AAA-ATPase in Proteasomal Degradation
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DOI：
10.1016/j.jmb.2009.09.050
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发表时间：
2009-12-11
影响因子：
5.6
通讯作者：
Young, Patrick
中科院分区：
文献类型：
--
作者：
Beskow, Anne;Grimberg, Kristian Bjork;Young, Patrick
多功能 AAA-ATPase p97 是真核细胞中最丰富、最保守的蛋白质之一。 p97/Np14/Ufd1 复合物使内质网中蛋白质质量控制失败的蛋白质发生移位。进入细胞质，在那里它们被泛素/蛋白酶体系统降解。底物错位取决于 p97 的解折叠酶活性。有趣的是，p97 还参与特定可溶性蛋白酶体底物的降解，但 p97 在此过程中的确切作用模式尚不清楚。在这里，我们表明 p97 的中心孔和 ATP 酶活性对于胞质泛素融合底物的降解是必需的。在底物中添加灵活的延伸 C 端肽可减轻对 p97 的需求。删除图谱揭示了该肽的 20 个残基的保守长度依赖性，这允许发生不依赖于 p97 的降解。我们的结果表明，解折叠的起始可能比之前预期的更加复杂，并且蛋白酶体的 19S 调节复合物可能需要 p(97Ufd1/Np14) 复合物对高度折叠的泛素化底物进行预处理。我们的数据解释了 p97 仅对某个亚群至关重要的观察结果。并预测可溶性 p97 依赖性底物的共同特征是缺乏促进 26S 蛋白酶体解折叠的起始位点。 (C) 2009 Elsevier Ltd. 保留所有权利。
The multifunctional AAA-ATPase p97 is one of the most abundant and conserved proteins in eukaryotic cells. The p97/Np14/Ufd1 complex dislocates proteins that fail the protein quality control in the endoplasmic reticulum. to the cytosol where they are subject to degradation by the ubiquitin/proteasome system. Substrate dislocation depends on the unfoldase activity of p97. Interestingly, p97 is also involved in the degradation of specific soluble proteasome substrates but the exact mode of action of p97 in this process is unclear. Here, we show that both the central pore and ATPase activity of p97 are necessary for the degradation of cytosolic ubiquitin-fusion substrates. Addition of a flexible extended C-terminal peptide to the substrate relieves the requirement for p97. Deletion mapping reveals a conserved length dependency of 20 residues for the peptide, which allows p97-independent degradation to occur. Our results suggest that initiation of unfolding may be more complex than previously anticipated and that the 19S regulatory complex of the proteasome can require preprocessing of highly folded, ubiquitylated substrates by the p(97Ufd1/Np14) complex. Our data provide an explanation for the observation that p97 is only essential for a subpopulation. of soluble substrates and predict that a common characteristic of soluble p97-dependent substrates is the lack of an initiation site to facilitate unfolding by the 26S proteasome. (C) 2009 Elsevier Ltd. All rights reserved.