SLO2, a mitochondrial pentatricopeptide repeat protein affecting several RNA editing sites, is required for energy metabolism
Pentatricopeptide repeat (PPR) proteins belong to a family of approximately 450 members in Arabidopsis, of which few have been characterized. We identified loss of function alleles of SLO2, defective in a PPR protein belonging to the E+ subclass of the P‐L‐S subfamily. slo2 mutants are characterized by retarded leaf emergence, restricted root growth, and late flowering. This phenotype is enhanced in the absence of sucrose, suggesting a defect in energy metabolism. The slo2 growth retardation phenotypes are largely suppressed by supplying sugars or increasing light dosage or the concentration of CO2. The SLO2 protein is localized in mitochondria. We identified four RNA editing defects and reduced editing at three sites in slo2 mutants. The resulting amino acid changes occur in four mitochondrial proteins belonging to complex I of the electron transport chain. Both the abundance and activity of complex I are highly reduced in the slo2 mutants, as well as the abundance of complexes III and IV. Moreover, ATP, NAD+, and sugar contents were much lower in the mutants. In contrast, the abundance of alternative oxidase was significantly enhanced. We propose that SLO2 is required for carbon energy balance in Arabidopsis by maintaining the abundance and/or activity of complexes I, III, and IV of the mitochondrial electron transport chain.
Document Type: Research Article
Affiliations: 1: Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K L Ledeganckstraat 35, B-9000 Ghent, Belgium 2: Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany 3: Institut de Biologie Moléculaire des Plantes (IBMP) du CNRS, 12 Rue du Général Zimmer, 67084 Strasbourg Cedex, France 4: Department of Plant Sciences, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK 5: Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Clarendon Way, Leeds LS2 9JT, UK 6: Section of Plant Genetics, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
Publication date: September 1, 2012