Impact of a mutation in the mitochondrial LSU rRNA gene from Chlamydomonas reinhardtii on the activity and the assembly of respiratory-chain complexes.
Two substitutions A1090G and A1098C (together called the m mutation) located in the conserved GTPase domain of the mitochondrial LSU rRNA gene were recently shown to weakly compensate for the phenotypical effect of a -1T frameshift mutation in the mitochondrial cox1 gene of C. reinhardtii. In order to analyze the impact of the m mutation on the mitochondrial translational machinery, a strain carrying the m mutation but wild-type for the cox1 gene was isolated. We found that the growth and the respiratory rate of the m mutant were affected and that the activities of complexes I, III, and IV, all containing mitochondria-encoded subunits, were lowered. In contrast the activities of complex II and of the alternative oxidase, both encoded exclusively by the nuclear genome, were not modified. The steady-state levels of complex I enzyme and of several components of the respiratory complexes I, III, and IV were also reduced in the mutant. We moreover showed that m did not suppress other frameshift or UGA stop mutations which affect mitochondrial genes.
Remacle
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C
Department of Life Sciences, Institute of Botany B22, University of Liège, Sart-Tilman, 4000, Liège, Belgium. c.remacle@ulg.ac.be
Gloire
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G
Cardol
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Matagne
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RF
D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D003580:Cytochromes / Q000378:metabolism; D004272:DNA, Mitochondrial; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D016368:Frameshift Mutation; D020459:Genes, rRNA; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D008957:Models, Genetic; D009154:Mutation; D010088:Oxidoreductases / Q000378:metabolism; D010101:Oxygen Consumption; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010940:Plant Proteins; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D012335:RNA, Ribosomal / Q000235:genetics*; D012270:Ribosomes / Q000648:ultrastructure*; D013045:Species Specificity; D000099188:Alternative Oxidase
D003580:Cytochromes; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D012335:RNA, Ribosomal; D000099188:Alternative Oxidase