Protein aggregation in plant mitochondria lacking Lon1 inhibits translation and induces unfolded protein responses

作者：Ce Song, Yuanyuan Li, Mengmeng Yang, Tiantian Li, Yuqi Hou, Yinyin Liu, Chang Xu, Jinjian Liu, A. Harvey Millar, Ning Ning Wang, Lie Li · 发表于：Plant Cell & Environment · 年份：2024 · DOI：10.1111/pce.15035 · 被引用次数：10 · 研究领域：Photosynthetic Processes and Mechanisms、Mitochondrial Function and Pathology、Plant responses to water stress

Loss of Lon1 led to stunted plant growth and accumulation of nuclear-encoded mitochondrial proteins including Lon1 substrates. However, an in-depth label-free proteomics quantification of mitochondrial proteins in lon1 revealed that the majority of mitochondrial-encoded proteins decreased in abundance. Additionally, we found that lon1 mutants contained protein aggregates in the mitochondrial that were enriched in metabolic enzymes, ribosomal subunits and PPR-containing proteins of the translation apparatus. These mutants exhibited reduced general mitochondrial translation as well as deficiencies in RNA splicing and editing. These findings support the role of Lon1 in maintaining a functional translational apparatus for mitochondrial-encoded gene translation. Transcriptome analysis of lon1 revealed a mitochondrial unfolded protein response reminiscent of the mitochondrial retrograde signalling dependent on the transcription factor ANAC017. Notably, lon1 mutants exhibited transiently elevated ethylene production, and the shortened hypocotyl observed in lon1 mutants during skotomorphogenesis was partially alleviated by ethylene inhibitors. Furthermore, the short root phenotype was partially ameliorated by introducing a mutation in the ethylene receptor ETR1. Interestingly, the upregulation of only a select few target genes was linked to ETR1-mediated ethylene signalling. Together this provides multiple steps in the link between loss of Lon1 and signalling responses to restore mit...