title: SLO2, a mitochondrial pentatricopeptide repeat protein affecting several RNA editing sites, is required for energy metabolism.
abstract: 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.
authors.affiliation: Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K L Ledeganckstraat 35, B-9000 Ghent, Belgium.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.forename: Jasper
authors.initials: J
authors.lastname: Dugardeyn
authors.forename: Chunyi
authors.initials: C
authors.lastname: Zhang
authors.forename: Mizuki
authors.initials: M
authors.lastname: Takenaka
authors.forename: Kristina
authors.initials: K
authors.lastname: Kühn
authors.forename: Christian
authors.initials: C
authors.lastname: Craddock
authors.forename: Jan
authors.initials: J
authors.lastname: Smalle
authors.forename: Michael
authors.initials: M
authors.lastname: Karampelias
authors.forename: Jurgen
authors.initials: J
authors.lastname: Denecke
authors.forename: Janny
authors.initials: J
authors.lastname: Peters
authors.forename: Tom
authors.initials: T
authors.lastname: Gerats
authors.forename: Axel
authors.initials: A
authors.lastname: Brennicke
authors.forename: Peter
authors.initials: P
authors.lastname: Eastmond
authors.forename: Etienne H
authors.initials: EH
authors.lastname: Meyer
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism*; D004734:Energy Metabolism; D018506:Gene Expression Regulation, Plant; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010641:Phenotype; D017393:RNA Editing; D013395:Sucrose / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; C000589711:SLO2 protein, Arabidopsis; C538752:pentatricopeptide repeat protein, Arabidopsis; D009243:NAD; D013395:Sucrose; D000255:Adenosine Triphosphate; D042967:Electron Transport Complex I