Arabidopsis mitochondrial membrane‐bound ubiquitin protease UBP27 contributes to mitochondrial morphogenesis

• Published in: The Plant journal : for cell and molecular biology Vol. 78; no. 6; pp. 1047 - 1059
• Main Authors: Pan, Ronghui, Kaur, Navneet, Hu, Jianping
• Format: Journal Article
• Language: English
• Published: England Blackwell Science 01.06.2014; Blackwell Publishing Ltd; Society for Experimental Biology
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - ultrastructure; Arabidopsis Proteins - analysis; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Arabidopsis thaliana; Bacteriology; BASIC BIOLOGICAL SCIENCES; bioinformatics; dynamin-related protein 3; enzyme activity; gene overexpression; guanosinetriphosphatase; mitochondria; Mitochondria - genetics; Mitochondria - metabolism; Mitochondria - ultrastructure; mitochondrial deubiquitinase; Mitochondrial DNA; mitochondrial dynamics; Mitochondrial Membranes - metabolism; Mitochondrial Membranes - ultrastructure; mitochondrial outer membrane; Morphogenesis; mutants; organelle division; phenotype; Plant biology; plant growth; Proteases; proteinases; Proteins; topology; ubiquitin; Ubiquitin-Specific Proteases - analysis; Ubiquitin-Specific Proteases - metabolism; Ubiquitin-Specific Proteases - physiology; Ubiquitination; UBP27; yeasts; Arabidopsis thaliana; UBP27; mitochondrial deubiquitinase; organelle division; mitochondrial outer membrane; dynamin-related protein 3; mitochondrial dynamics
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.12532

Mitochondria are essential organelles with dynamic morphology and function. Post‐translational modifications (PTMs), which include protein ubiquitination, are critically involved in animal and yeast mitochondrial dynamics. How PTMs contribute to plant mitochondrial dynamics is just beginning to be elucidated, and mitochondrial enzymes involved in ubiquitination have not been reported from plants. In this study, we identified an Arabidopsis mitochondrial localized ubiquitin protease, UBP27, through a screen that combined bioinformatics and fluorescent fusion protein targeting analysis. We characterized UBP27 with respect to its membrane topology and enzymatic activities, and analysed the mitochondrial morphological changes in UBP27T‐DNA insertion mutants and overexpression lines. We have shown that UBP27 is embedded in the mitochondrial outer membrane with an Nᵢₙ–Cₒᵤₜ orientation and possesses ubiquitin protease activities in vitro. UBP27 demonstrates similar sub‐cellular localization, domain structure, membrane topology and enzymatic activities with two mitochondrial deubiquitinases, yeast ScUBP16 and human HsUSP30, which indicated that these proteins are functional orthologues in eukaryotes. Although loss‐of‐function mutants of UBP27 do not show obvious phenotypes in plant growth and mitochondrial morphology, UBP27 overexpression can change mitochondrial morphology from rod to spherical shape and reduce the mitochondrial association of dynamin‐related protein 3 (DRP3) proteins, large GTPases that serve as the main mitochondrial fission factors. Thus, our study has uncovered a plant ubiquitin protease that plays a role in mitochondrial morphogenesis possibly through modulation of the function of organelle division proteins.