Glycoengineering of Cyanobacterial Thylakoid Membranes for Future Studies on the Role of Glycolipids in Photosynthesis

The lipid composition of thylakoid membranes is conserved from cyanobacteria to angiosperms. The pre-dominating components are monogalactosyl- and digalacto-syldiacylglycerol. In cyanobacteria, thylakoid membrane biosynthesis starts with the formation of monoglucosyldia-cylglycerol which is C4-epimerized to the corresponding galactolipid, whereas in plastids monogalactosyldiacylglyc-erol is formed at the beginning. This suggests that galactoli-pids have specific functions in thylakoids. We wanted to investigate whether galactolipids can be replaced by glyco-syldiacylglycerols with headgroups differing in their epimeric and anomeric details as well as the attachment point of the terminal hexose in diglycosyldiacylglycerols. For this purpose putative glycosyltransferase sequences were identified in databases to be used for functiona