The role of chloride ion in Photosystem II I. Effects of chloride ion on Photosystem II electron transport and on hydroxylamine inhibition

Kelley, Patrick M.; Izawa, S.

doi:10.1016/0005-2728(78)90042-7

Cited by 170 publications

(82 citation statements)

References 38 publications

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“…Figure 1 also provides evidence that other anions could replace Cl-as protecting agents with an order of effectiveness given by the sequence Cl-m Br-> N03 > F > C104 . Qualitatively, the ranking of the anions was identical to that of their ability to support the mechanism of water oxidation (18,24,28), with one notable exception: F-had some protective ability but is known to be an ineffective substitute of Cl-as a cofactor of the water oxidase (16,18,24,28).…”

Section: Methodsmentioning

confidence: 85%

“…Taking an alternative view, Govindjee's group (8, 17) and we (19,21) have proposed various mechanistic versions for a role of protein-bound Cl-in the deprotonation events accompanying water oxidation. Such an indirect participation of the anion in the catalytic process was postulated because of precedents in other enzyme systems (8,14) and to account for the reported need of more than one Cl-per ' Supported by grant DMB 8304416 from the National Science Foundation.water oxidizing complex (35), the unique pH dependence of Clbinding (21), the complex pattern of 35Cl-NMR line broadening (2, 10), and the ability of other monovalent anions such as NO3 to serve as rather efficient substitutes for 18,24,28).The Cl-relations of PSII are known to be greatly influenced by its extrinsic polypeptides of molecular masses 17 and 23 kD (12,23,30). By some yet unknown mechanism, these polypeptides cooperate in strengthening Cl-binding in the water oxidizing complex, thus allowing the retention of the anion in Cl--free media (19).…”

mentioning

confidence: 99%

“…water oxidizing complex (35), the unique pH dependence of Clbinding (21), the complex pattern of 35Cl-NMR line broadening (2,10), and the ability of other monovalent anions such as NO3 to serve as rather efficient substitutes for Cl- (16,18,24,28).…”

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confidence: 99%

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Homann¹

1988

Plant Physiol.

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To further our understanding of the role of Cl-and certain other monovalent anions in the oxygen evolving photosystem II of chloroplasts, dissociating and stabilizing anion effects on the extrinsic 17 and 23 kilodalton polypeptides of the photosynthetic water oxidizing complex were investigated. It was found that (a) the dissociation of the two polypeptides in Cl-free media of pH -7 was enhanced by millimolar concentrations of the divalent anion S042-and also by divalent cations like Mg2" and Ca2"; (b) the dissociation was opposed by relatively low concentrations of monovalent anions with an order of effectiveness Cl-= Br-> N03-> F > C104-; (c) at molar concentrations, S042-stabilized the binding of the 23 kilodalton polypeptide, while Cl-and Br-became dissociating agents, in agreement with studies by Blough and Sauer (1984 Biochim Biophys Acta 767: 377-381); (d) the binding of the polypeptides was strengthened at room temperature relative to 0°C, indicating an involvement of hydrophobic forces. It is suggested that a specific binding of Cl-, or certain substitutes, organizes the protein surfaces and/or the adjacent water layers in the water oxidizing complex in a way that not only stabilizes its assembly, but is essential for the catalytic mechanism as well. Binding of, or charge screening by, divalent ions interferes with this process. At high salt concentrations, all these effects are overridden by "lyotropic" actions of the solutes that affect the integrity of the water oxidizing protein complex by stabilizing or disrupting critical hydrophobic domains.Removal of Cl-from PSII of chloroplast thylakoids causes an aberration and interruption of the normal progress of charge accumulation in and perhaps around the Mn-cluster ofthe water oxidizing complex (for reviews, see Refs. 15, 17, and 21). However, the exact function of Cl-is not understood. Sandusky and Yocum (33) have proposed that an essential step in the mechanism of water oxidation is a ligation of Cl-to the Mn-cluster itself. This concept was developed on the basis of their finding that Cl-, in a competitive fashion, protected the water oxidizing mechanism from the inhibitory action of NH3 and various amines, the action of which was attributed to a binding to the oxidant storing Mn-complex. Taking an alternative view, Govindjee's group (8, 17) and we (19,21) have proposed various mechanistic versions for a role of protein-bound Cl-in the deprotonation events accompanying water oxidation. Such an indirect participation of the anion in the catalytic process was postulated because of precedents in other enzyme systems (8,14) and to account for the reported need of more than one Cl-per ' Supported by grant DMB 8304416 from the National Science Foundation.water oxidizing complex (35), the unique pH dependence of Clbinding (21), the complex pattern of 35Cl-NMR line broadening (2, 10), and the ability of other monovalent anions such as NO3 to serve as rather efficient substitutes for 18,24,28).The Cl-relations of PSII are known to be greatly influenc...

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Section: Methodsmentioning

confidence: 85%

mentioning

confidence: 99%

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Homann¹

1988

Plant Physiol.

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“…The function of Cl Ϫ in the OEC can be partially substituted by other anions, with the efficiency being Cl Ϫ Ϸ Br Ϫ Ͼ Ͼ NO 3 Ϫ Ͼ NO 2 Ϫ Ͼ I Ϫ (3,24). This phenomenon can be used to study the Cl Ϫ binding in the OEC, and indeed most previous studies have substituted Br Ϫ or other anions for Cl Ϫ to investigate its binding and function in the OEC.…”

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confidence: 99%

Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography

Kawakami

Umena

Kamiya

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

215

141

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The chloride ion, Cl ؊ , is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn 4Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl ؊ with a bromide ion (Br ؊ ) or an iodide ion (I ؊ ) in PSII and analyzed the crystal structures of PSII with Br ؊ and I ؊ substitutions. Substitution of Cl ؊ with Br ؊ did not inhibit oxygen evolution, whereas substitution of Cl ؊ with I ؊ completely inhibited oxygen evolution, indicating the efficient replacement of Cl ؊ by I ؊ . PSII with Br ؊ and I ؊ substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn 4Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn 4Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl ؊ anions are required to maintain the coordination structure of the Mn4Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active. membrane proteins ͉ oxygen evolution ͉ photosynthesis ͉ manganese enzyme P hotosynthetic water oxidation produces the oxygen required for life on the earth and is catalyzed by Photosystem II (PSII), a multiprotein complex with a total molecular mass of 350 kDa (1). The catalytic center for water splitting, i.e., the oxygen-evolving complex (OEC), is located in the membrane surface of the luminal side of thylakoid membranes and is composed of 4 Mn atoms and 1 Ca atom in the protein matrix of PSII. Oxygen is produced from 2 molecules of water by sequential, light-induced electron-abstracting events at the Mn 4 Ca cluster that cycle through the Si states with i ϭ 0-4 (2). One or more Cl Ϫ ions are required for the water oxidation cycle to proceed, a requirement not often found in other biological systems (3, 4). Depletion of Cl Ϫ has been shown to inhibit the S 2 3 S 3 and S 3 3 S 0 transitions (5). The roles of Cl Ϫ proposed for OEC include ligation to Mn or Ca atoms (6-8), regulation of the redox potential of the Mn 4 Ca cluster (9), maintaining a hydrogen bond network (10), and activation of the substrate water (11). In addition, an association of Cl Ϫ with amino acid residues in the Mn coordination shell has been proposed (12, 13).The structure of PSII, including the Mn 4 Ca cluster, has been analyzed by x-ray crystallography (14-17). These studies, together with polarized extended x-ray absorption fine structure (EXAFS) measurements (18), have provided much information about the structure of the Mn 4 Ca cluster. However, they did not provide any information about the number and location of Cl Ϫ ions within the OEC. The inhibition of particular S-state transitions upon depletion of Cl Ϫ has been taken as evidence of the close p...

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“…Moreover, its high concentration in coconut leaf tissues means that it acts as an osmoticum in maintaining tissue turgor during drought [7]. Furthermore, a certain number of studies on plants other than palms demonstrated the important role of chloride in photosynthesis [4] and particularly in photosystem II [9,13].…”

Section: Introductionmentioning

confidence: 99%

Effects of chlorine deficiency in the field on leaf gas exchanges in the PB121 coconut hybrid

Braconnier

Bonneau

1998

Agronomie

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The role of chloride ion in Photosystem II I. Effects of chloride ion on Photosystem II electron transport and on hydroxylamine inhibition

Cited by 170 publications

References 38 publications

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography

Effects of chlorine deficiency in the field on leaf gas exchanges in the PB121 coconut hybrid

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The role of chloride ion in Photosystem II I. Effects of chloride ion on Photosystem II electron transport and on hydroxylamine inhibition

Cited by 170 publications

References 38 publications

Structural Effects of Cl− and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl− and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography

Effects of chlorine deficiency in the field on leaf gas exchanges in the PB121 coconut hybrid

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Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II

Structural Effects of Cl⁻ and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II