Polyunsaturated lipids are important components of photosynthetic membranes. Xanthophylls are the main photoprotective agents, can assist in protection against light stress, and are crucial in the recovery from photoinhibition. We generated the xanthophyll- and polyunsaturated lipid-deficient ROAD mutant of Synechocystis sp. PCC6803 (Synechocystis) in order to study the little-known cooperative effects of lipids and carotenoids (Cars). Electron microscopic investigations confirmed that in the absence of xanthophylls the S-layer of the cellular envelope is missing. In wild-type (WT) cells, as well as the xanthophyll-less (RO), polyunsaturated lipid-less (AD), and the newly constructed ROAD mutants the lipid and Car compositions were determined by MS and HPLC, respectively. We found that, relative to the WT, the lipid composition of the mutants was remodeled and the Car content changed accordingly. In the mutants the ratio of non-bilayer-forming (NBL) to bilayer-forming (BL) lipids was found considerably lower. Xanthophyll to β-carotene ratio increased in the AD mutant. In vitro and in vivo methods demonstrated that saturated, monounsaturated lipids and xanthophylls may stabilize the trimerization of Photosystem I (PSI). Fluorescence induction and oxygen-evolving activity measurements revealed increased light sensitivity of RO cells compared to those of the WT. ROAD showed a robust increase in light susceptibility and reduced recovery capability, especially at moderate low (ML) and moderate high (MH) temperatures, indicating a cooperative effect of xanthophylls and polyunsaturated lipids. We suggest that both lipid unsaturation and xanthophylls are required for providing the proper structure and functioning of the membrane environment that protects against light and temperature stress.

• MeSH
• beta-karoten metabolismus   účinky záření   MeSH
• buněčná membrána genetika   metabolismus   účinky záření   ultrastruktura   MeSH
• časové faktory MeSH
• fenotyp MeSH
• fotosyntéza genetika   účinky záření   MeSH
• fotosystém I - proteinový komplex genetika   metabolismus   účinky záření   MeSH
• fyziologická adaptace MeSH
• fyziologický stres * MeSH
• genotyp MeSH
• membránové lipidy metabolismus   účinky záření   MeSH
• metabolismus lipidů genetika   účinky záření   MeSH
• mutace MeSH
• světlo * MeSH
• Synechocystis genetika   metabolismus   účinky záření   ultrastruktura   MeSH
• teplota * MeSH
• tylakoidy metabolismus   účinky záření   MeSH
• xanthofyly genetika   metabolismus   účinky záření   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH