title: Phosphatidylglycerol depletion affects photosystem II activity in Synechococcus sp. PCC 7942 cells.
abstract: The role of phosphatidylglycerol (PG) in photosynthetic membranes of cyanobacteria was analyzed in a Synechococcus sp. PCC 7942 mutant produced by inactivating its cdsA gene presumably encoding cytidine 5'-diphosphate-diacylglycerol synthase, a key enzyme in PG synthesis. In a medium supplemented with PG the Synechococcus sp. PCC 7942/DeltacdsA cells grew photoautotrophically. Depletion of PG in the medium resulted (a) in an arrest of cell growth and division, (b) in a suppression of O(2) evolving activity, and (c) in a modification of Chl fluorescence induction curves. Two-dimensional PAGE showed that in the absence of PG (a) the amount of the PSI monomers increased at the expense of the PSI trimers and (b) PSII dimers were decomposed into monomers. [(35)S]methionine labeling confirmed that PG depletion did not block the de novo synthesis of PSII proteins but slowed down the assembly of the newly synthesized D1 protein into PSII core complexes. Retailoring of PG was observed during PG depletion: the exogenously added artificial dioleoyl PG was transformed into photosynthetically more essential PG derivatives. Concomitantly with a decrease in PG content, SQDG content increased, but it could not restore photosynthetic activity.
authors.affiliation: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, P. O. Box 521, 6701 Szeged, Hungary.
authors.forename: Balázs
authors.initials: B
authors.lastname: Bogos
authors.forename: Bettina
authors.initials: B
authors.lastname: Ughy
authors.forename: Ildikó
authors.initials: I
authors.lastname: Domonkos
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Laczkó-Dobos
authors.forename: Josef
authors.initials: J
authors.lastname: Komenda
authors.forename: Leyla
authors.initials: L
authors.lastname: Abasova
authors.forename: Krisztián
authors.initials: K
authors.lastname: Cser
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
authors.forename: Anna
authors.initials: A
authors.lastname: Sallai
authors.forename: Hajime
authors.initials: H
authors.lastname: Wada
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Gombos
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005453:Fluorescence; D050356:Lipid Metabolism; D016254:Mutagenesis, Insertional; D010715:Phosphatidylglycerols / Q000378:metabolism / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; D010715:Phosphatidylglycerols; D045332:Photosystem II Protein Complex; D021122:Protein Subunits