Abstract
Almost all organisms have lipid modification systems required for anchoring soluble proteins to membranes. Bacterial lipoproteins are a set of proteins modified at their N-terminal cysteine residue with an N-acyl group and S-diacylglyceryl group. This type of lipid modification is ubiquitous in bacteria. Although the lipid modification of lipoproteins has been studied in some bacteria, it has not been studied in cyanobacteria. Because cyanobacteria are unique bacteria containing thylakoid membranes in addition to outer and plasma membranes, lipoproteins in cyanobacteria are expected to have many important roles. In this study, we identified all genes involved in lipid modification of lipoproteins in a cyanobacterium Synechocystis sp. PCC6803 and found that some subunits of the photosystem II complex are lipoproteins. These results suggested that the pathway of the lipid modification of lipoproteins exists in cyanobacteria and lipid modification has important roles in assembly of the subunits to the photosystem II complex.
