The Plant Mitochondrial Proteome

Plant mitochondria function in respiratory oxidation of organic acids and the transfer of electrons to oxygen via the respiratory electron transport chain, but also participate in wider catabolic and biosynthetic activities vital to plant growth and development. Over 2,000 different proteins are likely to be present in plant mitochondria and many have as yet undefined roles. A fuller systems understanding of the role of mitochondria will require continuing advancements in the isolation of high purity mitochondrial samples and an array of proteomic approaches to categorise their protein composition. In parallel to experimental analysis, prediction programs continue to be useful to search plant genome sequence data to identify putative mitochondrial proteins that are missing due to the physical and chemical limitations of current protein separation and analysis techniques. Studies on post-translational modifications (PTMs) of the primary sequence of mitochondrial proteins are providing important information on putative regulation and damage within the organelle but most such PTMs still need to be investigated in detail to define their biological significance. The interactions between proteins, and between proteins and ligands, define the large-scale structure of the mitochondrial proteome and we are beginning to undercover the dynamic interactions of this protein set, which defines the respiratory apparatus in plants.