The contribution of mitochondria to plant energy has a great impact on plant growth and development. In this project we plan a detailed functional characterization of SLO2, a mitochondrial protein which affects the accumulation of several key components in mitochondrial energy metabolism in plants. SLO2 belongs to the large family of pentatricopeptide repeat (PPR) proteins. This family contains approximately 450 members in Arabidopsis, of which only few were characterized. PPR proteins are generally involved in regulation of organelle genome expression, and are most often implicated in RNA editing. In this project we will focus on elucidation of the mechanism of SLO2 in regulation of RNA editing and the mitochondrial energy status by an in depth characterization of its protein interaction partners.