A Unique SUMO-Interacting Motif of Trx2 Is Critical for Its Mitochondrial Presequence Processing and Anti-oxidant Activity
A Unique SUMO-Interacting Motif of Trx2 Is Critical for Its Mitochondrial Presequence Processing and Anti-oxidant Activity
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Trx2 独特的 SUMO 相互作用基序对其线粒体前序处理和抗氧化活性至关重要
DOI：
10.3389/fphys.2019.01089
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发表时间：
2019-08-27
影响因子：
4
通讯作者：
Min, Wang
中科院分区：
文献类型：
--
作者：
Chen, Chaofei;Wang, Kang;Min, Wang
目的：线粒体硫氧还蛋白2 （Trx2）是一种重要的线粒体氧化还原蛋白，介导正常的蛋白质硫醇还原，并为过氧化物还蛋白3 （Prx3）提供电子，清除线粒体中的H2O2。Trx2缺失在细胞或小鼠中产生大量活性氧（reactive oxygen species， ROS），参与了许多病理过程，已被广泛报道。相反，ROS如何调节Trx2的加工和活性仍有待阐明。方法和结果：在这里，我们发现过量的ROS诱导内皮细胞衰老，同时Trx2加工的衰减，其中Trx2前置序列[即线粒体靶向信号肽（MTS）]被裂解以产生成熟的形式。突变分析表明，Trx2的加工是由MTS内的线粒体加工肽酶（MPP）和线粒体中间肽酶（MIP）识别位点介导的。有趣的是，SUMO相互作用基序（SIM）的突变，而不是成熟Trx2蛋白内的催化位点，完全阻断了Trx2的加工，而对Trx2的线粒体靶向没有影响。一致地，化学抑制蛋白的SUMOylation减弱，而SUMOylation激动剂促进Trx2加工。此外，我们发现α - mpp亚基是一种SUMOylated蛋白，可能介导trx2结合和切割。此外，未加工形式的Trx2-SIM不能保护细胞免受ROS生成和氧化应激诱导的细胞衰老。结论：我们的研究表明，Trx2的一个独特的sumo相互作用基序对其线粒体加工和随后的抗氧化/抗衰老活性至关重要。
Objective: Mitochondrial thioredoxin 2 (Trx2) is a vital mitochondrial redox protein that mediates normal protein thiol reduction and provides electrons to peroxiredoxin 3 (Prx3) to scavenge H2O2 in mitochondria. It has been widely reported that Trx2 deletion in cells or mice generates massive reactive oxygen species (ROS) which have been implicated in many pathological processes. On the contrary, how ROS regulate Trx2 processing and activity remains to be elucidated.Approach and Results: Here we show that excess ROS induce endothelial cell senescence concomitant with an attenuation of Trx2 processing in which Trx2 presequence [i.e., mitochondrial targeting signal peptide (MTS)] is cleaved to generate a mature form. Mutation analyses indicate that Trx2 processing is mediated by mitochondrial processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP)-recognition sites within the MTS. Interestingly, a mutation at a SUMO- interacting motif (SIM), but not the catalytic sites within the mature Trx2 protein, completely blocks Trx2 processing with no effect on Trx2 mitochondrial targeting. Consistently, chemical inhibition of protein SUMOylation attenuates, while SUMOylation agonist promotes, Trx2 processing. Moreover, we identify the alpha-MPP subunit is a SUMOylated protein that potentially mediates Trx2-binding and cleavage. Furthermore, the unprocessed form of Trx2-SIM is unable to protect cells from both ROS generation and oxidative stress-induced cellular senescence.Conclusion: Our study reveals that a unique SUMO-interacting motif of Trx2 is critical for its mitochondrial processing and subsequent anti-oxidant/antisenescence activities.