Triacylglycerol and phytyl ester synthesis in Synechocystis sp. PCC6803

Significance Cyanobacteria harbor a photosynthetic apparatus related to plant chloroplasts. The lipid compositions of the thylakoids that harbor the photosynthetic complexes in cyanobacteria and chloroplasts are highly similar. Chloroplasts contain triacylglycerol (storage oil) and wax esters; the latter are composed of phytol derived from chlorophyll and fatty acids (phytyl esters). However, the existence of these lipids in cyanobacteria in general remained unclear. Here we show that the cyanobacterium Synechocystis contains triacylglycerol and phytyl esters. A mutant, Δslr2103, was generated, which lacked these two lipids but showed no obvious growth defect. The slr2103 gene encodes a diacylglycerol acyltransferase different from known enzymes of triacylglycerol synthesis in bacteria. This pathway can be employed to produce oil for biotechnological applications in cyanobacteria.