Characterization of FtsH proteases in the annual plant Arabidopsis thaliana

Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope. Methods Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers. Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants. Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins.