Gross morphological changes in thylakoid membrane structure are associated with photosystem I deletion in Synechocystis sp. PCC 6803

► Deletion of cyanobacterial PSII led to tubes of thylakoids instead of sheets. ► Deletion of PSI and PSII reduced the total number of thylakoid membranes. ► Phycobilisome arrangement was altered in the mutant lacking PSI and PSII.