Complexome Profiling Reveals Association of PPR Proteins with Ribosomes in the Mitochondria of Plants[S]

• Published in: Molecular & cellular proteomics Vol. 18; no. 7; pp. 1345 - 1362
• Main Authors: Rugen, Nils, Straube, Henryk, Franken, Linda E., Braun, Hans-Peter, Eubel, Holger
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2019; The American Society for Biochemistry and Molecular Biology
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Bacteria - metabolism; complexome; Crosslinking; mitochondria; Mitochondria - metabolism; Mitochondria function or biology; Mitochondrial Proteins - metabolism; Molecular Weight; Multiprotein Complexes - metabolism; plant; Plant Biology; Plant Leaves - metabolism; PPR; Protein Subunits - metabolism; Proteomics; Ribosomal Proteins - metabolism; ribosome; Ribosome Subunits, Large - metabolism; Ribosome Subunits, Small - metabolism; Ribosomes; Ribosomes - metabolism; Translation; Plant Biology; Translation; PPR; mitochondria; Ribosomes; plant; complexome; Crosslinking; ribosome; Mitochondria function or biology
• DOI: 10.1074/mcp.RA119.001396
• ISSN: 1535-9476; 1535-9484

Plant mitochondrial protein expression is complex and routinely involves pentatricopeptide repeat proteins for processing of transcripts. Although the composition and structure of the mitoribosomes in other eukaryotic kingdoms of life is well established, plant mitochondria have so far eluded a detailed analysis. Using a complexome profiling approach, this study provides an early glimpse on the composition of plant mitochondrial ribosomes and sheds new light on the process of mitochondrial gene expression in plants. Mitochondrial subunits were found to possess several additional proteins carrying pentatricopeptide repeats potentially involved in RNA editing. Other proteins are potentially involved in the processing of nascent proteins. [Display omitted] Highlights •Plant mitoribosomes contain several pentatricopeptide repeat proteins.•The small mitoribosomal subunit is of an exceptionally large size.•Protein units not directly related to translation may be attached to plant mitoribosomes to confer additional functions to these molecular machines. Mitochondrial transcripts are subject to a wealth of processing mechanisms including cis- and trans-splicing events, as well as base modifications (RNA editing). Hundreds of proteins are required for these processes in plant mitochondria, many of which belong to the pentatricopeptide repeat (PPR) protein superfamily. The structure, localization, and function of these proteins is only poorly understood. Here we present evidence that several PPR proteins are bound to mitoribosomes in plants. A novel complexome profiling strategy in combination with chemical crosslinking has been employed to systematically define the protein constituents of the large and the small ribosomal subunits in the mitochondria of plants. We identified more than 80 ribosomal proteins, which include several PPR proteins and other non-conventional ribosomal proteins. These findings reveal a potential coupling of transcriptional and translational events in the mitochondria of plants. Furthermore, the data indicate an extremely high molecular mass of the “small” subunit, even exceeding that of the “large” subunit.