Danja Schünemann - Protein transport to the thylakoid membrane of chloroplasts – Insights into evolution and mechanisms

The biogenesis of photosynthetic protein complexes of the chloroplast thylakoid membrane requires highly specific protein sorting, integration and assembly mechanisms of nucleus as well as plastid encoded subunits. Nuclear encoded subunits are posttranslationally imported into the chloroplast and further directed to the thylakoid membrane or the thylakoid lumen by various distinct mechanisms: the chloroplast secretory (cpSec), the chloroplast twin-arginine (cpTat), the chloroplast signal recognition particle/albino 3 (cpSRP/Alb3) and the spontaneous insertion pathway. The chloroplast genome encodes only a f ew proteins. However, among them are several essential subunits of the photosynthetic complexes which are synthesized on thylakoid-bound ribosomes and cotranslationally inserted into the membrane. My talk will focus on the evolution of the chloroplast transport machineries and highlight recent advances in understanding the molecular details of the cotranslational targeting of photosynthetic key proteins.