Investigation of the mitochondrial protease profile in plants and functional characterization of CLPP2

Proteolysis in plant mitochondria plays an essential role in the proper function of oxidative phosphorylation (OXPHOS) machinery and its adaption to environmental stress.
In this thesis, bioinformatics was used to identify 63 candidate mitochondrial proteases in the model plant Arabidopsis thaliana and CLPP2 was chosen for in-depth analysis.
Two CLPP2 knock out mutants were built using CRISPR-Cas9 technology and each showed a minor root phenotype under nitrogen starvation scenarios.
Contrary to the minor phenotypical impact on whole plants, these mutants had higher abundance of transcripts from mitochondrial genes encoding OXPHOS components, while transcripts from nuclear genes encoding other subunits of the same OXPHOS complexes showed no change in abundance. The inverse effect was shown on OXPHOS protein abundances, notably nuclear subunits of specific modules of OXPHOS Complexes I and V accumulated in mutants likely due to the influence of CLPP2 on their assembly or maintenance.