title: Salt stress inhibits photosystems II and I in cyanobacteria.
abstract: Recent studies of responses of cyanobacterial cells to salt stress have revealed that the NaCl-induced decline in the photosynthetic activities of photosystems II and I involves rapid and slow changes. The rapid decreases in the activities of both photosystems, which occur within a few minutes, are reversible and are associated with osmotic effects, which induce the efflux of water from the cytosol through water channels and rapidly increase intracellular concentrations of salts. Slower decreases in activity, which occur within hours, are irreversible and are associated with ionic effects that are due to the influx of Na(+) and Cl(-) ions through K(+)(Na(+)) channels and, probably, Cl(-) channels, with resultant dissociation of extrinsic proteins from photosystems. In combination with light stress, salt stress significantly stimulates photoinhibition by inhibiting repair of photodamaged photosystem II. Tolerance of photosystems to salt stress can be enhanced by genetically engineered increases in the unsaturation of fatty acids in membrane lipids and by intracellular synthesis of compatible solutes, such as glucosylglycerol and glycinebetaine. In this review, we summarize recent progress in research on the effects of salt stress on photosynthesis in cyanobacteria.
authors.affiliation: Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia.
authors.forename: Suleyman I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: Norio
authors.initials: N
authors.lastname: Murata
mesh_terms: D000222:Adaptation, Physiological; D000458:Cyanobacteria / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004579:Electron Transport; D004734:Energy Metabolism; D005227:Fatty Acids / Q000378:metabolism; D008027:Light; D008563:Membrane Lipids / Q000378:metabolism; D009997:Osmotic Pressure; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D054712:Salinity; D012965:Sodium Chloride / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride