Conserved proline residues in the coiled coil-OB domain linkers of Rpt proteins facilitate eukaryotic proteasome base assembly.
Conserved proline residues in the coiled coil-OB domain linkers of Rpt proteins facilitate eukaryotic proteasome base assembly.
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DOI：
10.1016/j.jbc.2021.100660
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Hochstrasser M
中科院分区：
文献类型：
--
作者：
Cheng CL;Wong MK;Li Y;Hochstrasser M
蛋白酶体是一种大的蛋白酶复合物，降解许多不同的细胞蛋白质。在真核生物中，26 S蛋白酶体包含与不同细胞活性相关的ATP酶家族的六个不同亚基，Rpt 1-Rpt 6，其形成六聚体环作为驱动底物解折叠和易位到蛋白酶体核心的碱基亚复合物的一部分。质膜蛋白酶体仅含有一种与多种细胞活性相关的Rpt样ATP酶ATP酶，即蛋白酶体激活核苷酸酶，它形成二聚体的三聚体。一个关键的蛋白酶体激活核苷酸酶脯氨酸残基（P91）在环周围的连续亚基中形成顺式和反式肽键，允许通过上游卷曲螺旋进行有效的二聚化。然而，等价的Rpt脯氨酸对真核蛋白酶体组装的重要性尚不清楚。在这里，我们表明，相当于脯氨酸是高度保守的Rpt 2，Rpt 3和Rpt 5，和松散保守的Rpt 1，在非常分歧的真核生物。虽然在任何情况下，是一个单一的前丙氨酸取代芽殖酵母生长强烈有害，rpt 5-P76 A突变降低蛋白质水平，并诱导轻度蛋白酶体组装缺陷。此外，rpt 2-P103 A、rpt 3-P93 A和rpt 5-P76 A突变在与特定蛋白酶体碱基组装伴侣缺失组合时均引起合成缺陷。rpt 2-P103 A rpt 5-P76 A双突变体具有独特的强生长缺陷，这归因于蛋白酶体碱基形成缺陷。该突变体中的几个Rpt亚基形成聚集体，其至少部分通过Hsp 42分子伴侣介导的蛋白质质量控制被清除。我们建议，保守的Rpt接头脯氨酸促进有效的26 S蛋白酶体碱基组装，促进特定的ATP酶异源二聚化。
The proteasome is a large protease complex that degrades many different cellular proteins. In eukaryotes, the 26S proteasome contains six different subunits of the ATPases associated with diverse cellular activities family, Rpt1–Rpt6, which form a hexameric ring as part of the base subcomplex that drives unfolding and translocation of substrates into the proteasome core. Archaeal proteasomes contain only a single Rpt-like ATPases associated with diverse cellular activities ATPase, the proteasome-activating nucleotidase, which forms a trimer of dimers. A key proteasome-activating nucleotidase proline residue (P91) forms cis- and trans-peptide bonds in successive subunits around the ring, allowing efficient dimerization through upstream coiled coils. However, the importance of the equivalent Rpt prolines for eukaryotic proteasome assembly was unknown. Here we showed that the equivalent proline is highly conserved in Rpt2, Rpt3, and Rpt5, and loosely conserved in Rpt1, in deeply divergent eukaryotes. Although in no case was a single Pro-to-Ala substitution in budding yeast strongly deleterious to growth, the rpt5–P76A mutation decreased levels of the protein and induced a mild proteasome assembly defect. Moreover, the rpt2–P103A, rpt3–P93A, and rpt5–P76A mutations all caused synthetic defects when combined with deletions of specific proteasome base assembly chaperones. The rpt2–P103A rpt5–P76A double mutant had uniquely strong growth defects attributable to defects in proteasome base formation. Several Rpt subunits in this mutant formed aggregates that were cleared, at least in part, by Hsp42 chaperone-mediated protein quality control. We propose that the conserved Rpt linker prolines promote efficient 26S proteasome base assembly by facilitating specific ATPase heterodimerization.
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作者：
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DOI：
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发表时间：
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影响因子：
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