Structure and function of Vms1 and Arb1 in RQC and mitochondrial proteome homeostasis
Structure and function of Vms1 and Arb1 in RQC and mitochondrial proteome homeostasis
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DOI：
10.1038/s41586-019-1307-z
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发表时间：
2019-06-27
期刊：
影响因子：
64.8
通讯作者：
Beckmann, Roland
中科院分区：
文献类型：
--
作者：
Su, Ting;Izawa, Toshiaki;Beckmann, Roland
核糖体相关质量控制（RQC）为真核细胞提供了一种拯救途径，以在胞质核糖体翻译停滞后处理错误蛋白质（1-6）。核糖体解离后，停滞的tRNA结合肽仍与60 S亚基结合，并通过添加C-末端丙氨酰和苏氨酰残基（CAT尾）由Rqc 2延伸（7-9），而Vms 1在添加CAT尾之前或之后催化肽基-tRNA的切割和释放（10-12）。在这样做的过程中，Vms 1抵消了核编码的线粒体蛋白的CAT拖尾，否则会驱动聚集并损害线粒体和细胞的稳态（13）。在这里，我们提出的结构和功能的见解，酿酒酵母Vms 1与60 S亚基的相互作用，在前和后肽基-tRNA切割状态。Vms 1通过其Vms 1样释放因子1（VLRF 1）、锌指和锚蛋白结构域与60 S亚基结合。VLRF 1与Rqc 2 A-tRNA位置重叠，并与核糖体A位点相互作用，将其催化GSQ基序投射到tRNA的CCA末端，其Y285残基驱逐tRNA A73进行核裂解。此外，在前状态下，我们发现ABCF型ATP酶Arb 1位于核糖体E位点，其稳定肽基-tRNA的离域A73并刺激Vms 1依赖的tRNA切割。我们的结构分析提供了RQC因子Vms 1，Rqc 2和Arb 1的相互作用及其在保护线粒体免受毒性蛋白聚集中的作用的机制见解。
Ribosome-associated quality control (RQC) provides a rescue pathway for eukaryotic cells to process faulty proteins after translational stalling of cytoplasmic ribosomes(1-6). After dissociation of ribosomes, the stalled tRNA-bound peptide remains associated with the 60S subunit and extended by Rqc2 by addition of C-terminal alanyl and threonyl residues (CAT tails)(7-9), whereas Vms1 catalyses cleavage and release of the peptidyl-tRNA before or after addition of CAT tails(10-12). In doing so, Vms1 counteracts CAT-tailing of nuclear-encoded mitochondrial proteins that otherwise drive aggregation and compromise mitochondrial and cellular homeostasis(13). Here we present structural and functional insights into the interaction of Saccharomyces cerevisiae Vms1 with 60S subunits in pre-and post-peptidyl-tRNA cleavage states. Vms1 binds to 60S subunits with its Vms1-like release factor 1 (VLRF1), zinc finger and ankyrin domains. VLRF1 overlaps with the Rqc2 A-tRNA position and interacts with the ribosomal A-site, projecting its catalytic GSQ motif towards the CCA end of the tRNA, its Y285 residue dislodging the tRNA A73 for nucleolytic cleavage. Moreover, in the pre-state, we found the ABCF-type ATPase Arb1 in the ribosomal E-site, which stabilizes the delocalized A73 of the peptidyl-tRNA and stimulates Vms1-dependent tRNA cleavage. Our structural analysis provides mechanistic insights into the interplay of the RQC factors Vms1, Rqc2 and Arb1 and their role in the protection of mitochondria from the aggregation of toxic proteins.