Genesis and evolution of photosynthetic membranes

Abstract

Oxygenic photosynthesis is generally localized to thylakoid membranes both in prokaryotic and eukaryotic organisms. In contrast in oxygene photosynthesis is localized to plasma membrane. It seems therefore reasonable to assume that the genesis of thylakoids was a prerequisite or at least occurred concomitantly with the establishment of oxygenic photosynthesis. Today we know four different pathways by which proteins can be transported into thylakoids, e.g. Sec-, Tat-, SRP and spontaneous insertion pathway. However the protein translocation pathways require preexisting membranes to function. Fusion of vesicles budding off the inner membrane could be one mechanism by which thylakoids form. Our results show that an active vesicular transport system exists in chloroplasts, which is highly regulated by nucleotides and phosphorylation. We have isolated VIPP 1 deletion mutants from (vesicle including plastid protein) Arabidopsis and Synechocystis, which are devoid of thylakoid membranes and consequently unable to carry out oxygenic photosynthesis. Our data open new avenues to investigate the genesis and evolution of thylakoids