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'Salt Mediated Effects' in keywords Facet   Publication Year 1998  [X]
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1998[X]
1Author    E.K N Én, N. Én, É. Th, M. F. RagataRequires cookie*
 Title    Effect of MgCl2 and Phosphatidylglycerol on CaCl2-Mediated Recovery of Oxygen Evolution in a Photosystem II Complex Depleted of the 17 and 24 kDa Extrinsic Proteins  
 Abstract    Phosphatidylglycerol (PG) is an anionic lipid of the thylakoid m em brane of higher plant chloroplasts. PG was shown previously to stimulate the evolution of oxygen in intact pho­ tosystem II (PSII) membranes [Fragata, M., Strzalka, K. and Nenonene, E. K. (1991) J. Pho-tochem. Photobiol. B: Biol 11, 329-342], In this work, a study was undertaken of the effect of MgCl2 and PG on the CaCl2-mediated recovery of oxygen evolution in a PSII complex depleted of the extrinsic proteins (EP) of molecular masses 17 kDa (EP17) and 24 kDa (EP24), hereunder designated d 1724PSII. This molecular system is structurally close to the PSII core complex of cyanobacteria and is therefore useful in the comparative analysis of PSII-PG relationships in cyanobacteria and the higher plants. This work reveals a new aspect of the thylakoid lipids role in the PSII function, namely the PG effect on intact PSII is observed as well in d 1724PSII. The results show that phosphatidylglycerol has the ability to compensate for the loss of EP17 and EP24 in the PSII complex. That is, PG restores the oxygen evolution in d 1724PSII incubated in the presence of MgCl2 and/or CaCl2 to the levels observed in native PSII. M oreover, the site of H 20 degradation in d 17 24PSII, including most probably the pool of calcium and chloride ions, would seem to be protected by phosphatidyl­ glycerol. This suggests that one of the docking sites of PG in the PSII complex is near EP24, inasmuch as this extrinsic protein participates in the regulation of the affinity of the calcium and chloride ions to the water oxidation site. Furtherm ore, taking into account that in d j7 24PSII the PSII core complex is directly exposed to PG, then the phospholipid effect reported here indicates that phosphatidylglycerol might be a functional effector and mem­ brane anchor of the D1 protein in the PSII core complex as was shown recently in the cyanobacterium Oscillatoria chalybea [Kruse, O. and Schmid, G. H. (1995) Z. Naturforsch. 50c, 380-390], 
  Reference    Z. Naturforsch. 53c, 39—4 (1998); received September 1/October 24 1997 
  Published    1998 
  Keywords    Extrinsic Proteins, Oxygen Evolution Recovery, Phosphatidylglycerol, Photosystem II, Salt-Mediated Effects 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-0039.pdf 
 Identifier    ZNC-1998-53c-0039 
 Volume    53