Disrupting Autophagy Restores Peroxisome Function to an Arabidopsis lon2 Mutant and Reveals a Role for the LON2 Protease in Peroxisomal Matrix Protein Degradation
Disrupting Autophagy Restores Peroxisome Function to an Arabidopsis lon2 Mutant and Reveals a Role for the LON2 Protease in Peroxisomal Matrix Protein Degradation
复制标题
DOI：
10.1105/tpc.113.113407
复制
发表时间：
2013-10-01
期刊：
影响因子：
11.6
通讯作者：
Bartel, Bonnie
中科院分区：
文献类型：
--
作者：
Farmer, Lisa M.;Rinaldi, Mauro A.;Bartel, Bonnie
过氧化物酶体进行对幼苗发育至关重要的关键代谢反应。随着幼苗的成熟，代谢需求发生变化，过氧化物酶体的含量被重塑。常驻过氧化物酶体蛋白酶LON2定位于降解过时或受损的过氧化物酶体蛋白，但在植物中支持这种作用的数据仍然难以捉摸。拟南芥lon2突变体在过氧化物酶体代谢和基质蛋白输入方面表现出缺陷，但在基质蛋白降解方面表现正常。为了阐明LON2的功能，我们对LON2抑制子进行了前向遗传筛选，发现了关键自噬基因的多个突变。核心自噬相关基因（ATG）产物的失能会阻止自噬，自噬是胞质成分（包括细胞器）可以被液泡降解的过程。我们发现atg2， atg3和atg7突变抑制了lon2在生长素代谢和基质蛋白加工中的缺陷，挽救了lon2过氧化物酶体的异常大而少。此外，对lon2 atg突变体的分析揭示了lon2在基质蛋白周转中的明显作用。我们的数据表明，在过氧化物酶体内容重塑过程中，LON2促进了基质蛋白的降解，为植物中存在自噬提供了证据，并表明当LON2缺失时，自噬对过氧化物酶体的破坏会增强。
Peroxisomes house critical metabolic reactions that are essential for seedling development. As seedlings mature, metabolic requirements change, and peroxisomal contents are remodeled. The resident peroxisomal protease LON2 is positioned to degrade obsolete or damaged peroxisomal proteins, but data supporting such a role in plants have remained elusive. Arabidopsis thaliana lon2 mutants display defects in peroxisomal metabolism and matrix protein import but appear to degrade matrix proteins normally. To elucidate LON2 functions, we executed a forward-genetic screen for lon2 suppressors, which revealed multiple mutations in key autophagy genes. Disabling core autophagy-related gene (ATG) products prevents autophagy, a process through which cytosolic constituents, including organelles, can be targeted for vacuolar degradation. We found that atg2, atg3, and atg7 mutations suppressed lon2 defects in auxin metabolism and matrix protein processing and rescued the abnormally large size and small number of lon2 peroxisomes. Moreover, analysis of lon2 atg mutants uncovered an apparent role for LON2 in matrix protein turnover. Our data suggest that LON2 facilitates matrix protein degradation during peroxisome content remodeling, provide evidence for the existence of pexophagy in plants, and indicate that peroxisome destruction via autophagy is enhanced when LON2 is absent.