Knockdown of mitochondrialatp1mRNA by a custom-designed pentatricopeptide repeat protein alters F1FoATP synthase

Abstract

ABSTRACTWe show that a custom-designed RNA-binding protein binds and specifically induces cleavage ofatp1RNA in mitochondria, significantly decreasing the abundance of the Atp1 protein and the assembled F1FoATP synthase inArabidopsis thaliana. The transformed plants are characterized by delayed vegetative growth and reduced fertility. Five-fold depletion of Atp1 level was accompanied by a decrease in abundance of other ATP synthase subunits, lowered ATP synthesis rate of isolated mitochondria, but no change to mitochondrial electron transport chain complexes, adenylates or energy chargein planta. Transcripts for amino acid transport and a variety of stress response processes were differentially expressed in lines containing the PPR protein, indicating changes to achieve cellular homeostasis when ATP synthase was highly depleted. Leaves of ATP-synthase-depleted lines showed higher respiratory rates and elevated levels of most amino acids at night, most notably serine family amino acids. The results show the value of using custom-designed PPR proteins to influence expression of specific mitochondrial transcripts to carry out reverse genetics studies on mitochondrial gene functions and the consequences of ATP synthase depletion on cellular functions inArabidopsis.One sentence SummaryKnockdown of mitochondrialatp1mRNA by a custom-designed pentatricopeptide repeat protein alters F1Fo ATP synthase, plant growth and amino acid metabolism and ATP synthesis inArabidopsis thaliana