| | 1 | Author
| E.K N Én, N. Én, É. Th, M. F. Ragata | Requires 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 | |
| 2 | Author
| AlexanderG. Ivanov, MiraC. Busheva, MayaY. Velitchkova | Requires cookie* | | | Title
| Surface Charge Density Changes in Isolated Photosystem II Membranes Induced by Depletion of the Extrinsic Polypeptides of the Oxygen Evolving System | | | | Abstract
| Treatment of PS II particles with either 1 m NaCl or alkaline Tris (1 m , pH 8.4) caused a considerable decrease in the average net negative surface charge density, concomitant with de pletion of the extrinsic 17, 24 and 33 kDa proteins of the oxygen evolving complex from the membranes. The partial recovery of the values for surface charge in both NaCl-and Tris-treat-ed membranes was registered after reconstitution experiments with the three proteins. These results are compared with the data for the charge densities of the thylakoid membranes, to examine the role of the three extrinsic proteins in the formation of heterogeneous arrangement of surface charge across the appressed (granal) thylakoids. | | | |
Reference
| Z. Naturforsch. 45c, 627—632 (1990); received February 14 1990 | | | |
Published
| 1990 | | | |
Keywords
| Photosystem II Membranes, Surface Charge Density, Extrinsic Proteins, Protein Binding, 9-Aminoacridine | | | |
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| default:Reihe_C/45/ZNC-1990-45c-0627.pdf | | | | Identifier
| ZNC-1990-45c-0627 | | | | Volume
| 45 | |
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