Extrinsic 33-kilodalton protein of spinach oxygen-evolving complexes: kinetic studies of folding and disulfide reduction

Tanaka, Satoshi; Kawata, Yasushi; Wada, Keishiro; Hamaguchi, Kozo

doi:10.1021/bi00444a009

Cited by 40 publications

(64 citation statements)

References 30 publications

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“…Since the 23-kDa protein cannot directly associate with the 33-kDa protein in solution (24), these results suggest that binding of the 33-kDa protein to PSII alters the conformation of the protein itself which is essential for binding of the 23-kDa protein. The occurrence of a structural change of the protein is consistent with results of pH-dependent structural changes (38), effects of genetic or chemical modification of its disulfide-forming cysteines (39,40), or the effects of conformational constrains resulting from other amino acid substitutions (41).…”

Section: Characterization Of Intramolecularly Cross-linked 33-kda Prosupporting

confidence: 69%

“…Two Cys residues (Cys 28 and Cys 51 ) of the protein form a disulfide bond important for maintaining the functional structure of the protein (40,45,47). The secondary structural analysis of the 33-kDa protein in solution by far-UV CD spectroscopy revealed that the protein contains a large proportion of ␤-sheet and a relatively small amount of ␣-helical structure (48 (27).…”

Section: Characterization Of Intramolecularly Cross-linked 33-kda Promentioning

confidence: 99%

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Intramolecular Cross-linking of the Extrinsic 33-kDa Protein Leads to Loss of Oxygen Evolution but Not Its Ability of Binding to Photosystem II and Stabilization of the Manganese Cluster

Enami¹,

Kamo²,

Ohta³

et al. 1998

Journal of Biological Chemistry

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The extrinsic 33-kDa protein of photosystem II (PSII) was intramolecularly cross-linked by a zero-length cross-linker, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The resulting cross-linked 33-kDa protein rebound to urea/NaCl-washed PSII membranes, which stabilized the binding of manganese as effectively as the untreated 33-kDa protein. In contrast, the oxygen evolution was not restored by binding of the cross-linked protein, indicating that the binding and manganese-stabilizing capabilities of the 33-kDa protein are retained but its reactivating ability is lost by intramolecular cross-linking of the protein. From measurements of CD spectra at high temperatures, the secondary structure of the intramolecularly cross-linked 33-kDa protein was found to be stabilized against heat treatment at temperatures 20°C higher than that of the untreated 33-kDa protein, suggesting that structural flexibility of the 33-kDa protein was much decreased by the intramolecular cross-linking. The rigid structure is possibly responsible for the loss of the reactivating ability of the 33-kDa protein, which implies that binding of the 33-kDa protein to PSII is accompanied by a conformational change essential for the reactivation of oxygen evolution. Peptide mapping, N-terminal sequencing, and mass spectroscopic analysis of protease-digested products of the intramolecularly cross-linked 33-kDa protein revealed that cross-linkings occurred between the amino group of Lys 48 and the carboxyl group of Glu 246, and between the carboxyl group of Glu 10 and the amino group of Lys 14. These cross-linked amino acid residues are thus closely associated with each other through electrostatic interactions. PSII1 is a multisubunit pigment-protein complex which catalyzes the light-driven oxidation of water to molecular oxygen and the reduction of plastoquinone to plastoquinol. The minimum unit for PSII capable of oxygen evolution under physiological conditions contains seven major intrinsic proteins of the reaction center peptides D1 and D2, two apoproteins of cytochrome b 559 , psbI gene product, and two chlorophyll-binding peptides CP47 and CP43, and three extrinsic proteins of 33, 23, and 17 kDa which are associated with the lumenal surface of thylakoid membranes (1-3). The extrinsic 23-and 17-kDa proteins play a role in regulating the PSII affinity for calcium and chloride, and can be removed by treatment with 1.0 -2.0 M NaCl (4 -9). In cyanobacterial and red algal PSII, these two extrinsic proteins are absent, but a low-potential cytochrome c 550 and a 12-kDa protein have been found as the alternative extrinsic components (10 -12). The extrinsic 33-kDa protein, on the other hand, is present in all oxygenic photosynthetic organisms from cyanobacteria to higher plants and plays an important role in stabilizing binding and maintaining functional conformation of the manganese cluster which directly catalyzes the H 2 O-splitting reaction (for reviews, see Refs. 13-15). Removal of the 33-kDa protein from PSII membranes by washing with high concentrati...

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Section: Characterization Of Intramolecularly Cross-linked 33-kda Prosupporting

confidence: 69%

Section: Characterization Of Intramolecularly Cross-linked 33-kda Promentioning

confidence: 99%

Intramolecular Cross-linking of the Extrinsic 33-kDa Protein Leads to Loss of Oxygen Evolution but Not Its Ability of Binding to Photosystem II and Stabilization of the Manganese Cluster

Enami¹,

Kamo²,

Ohta³

et al. 1998

Journal of Biological Chemistry

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“…Interestingly, PsbO, a lumenal subunit of PSII required for stable assembly of the OEC, was shown to carry a single intramolecular disulfide that is strictly conserved in cyanobacteria and photosynthetic eukaryotes. In vitro studies established that this disulfide bond is critical to maintain the tertiary structure of PsbO (Tanaka et al, 1989;Betts , 1996;Wyman and Yocum, 2005). In chloroplast lumenal extracts, reduction of the disulfide in PsbO1 and PsbO2 targets the proteins for degradation.…”

Section: The Redox Activity Of Lto1 Is Required For the Assembly Of Psiimentioning

confidence: 99%

Lumen Thiol Oxidoreductase1, a Disulfide Bond-Forming Catalyst, Is Required for the Assembly of Photosystem II inArabidopsis

et al. 2011

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Here, we identify Arabidopsis thaliana Lumen Thiol Oxidoreductase1 (LTO1) as a disulfide bond-forming enzyme in the thylakoid lumen. Using topological reporters in bacteria, we deduced a lumenal location for the redox active domains of the protein. LTO1 can partially substitute for the proteins catalyzing disulfide bond formation in the bacterial periplasm, which is topologically equivalent to the plastid lumen. An insertional mutation within the LTO1 promoter is associated with a severe photoautotrophic growth defect. Measurements of the photosynthetic activity indicate that the lto1 mutant displays a limitation in the electron flow from photosystem II (PSII). In accordance with these measurements, we noted a severe depletion of the structural subunits of PSII but no change in the accumulation of the cytochrome b 6 f complex or photosystem I. In a yeast two-hybrid assay, the thioredoxin-like domain of LTO1 interacts with PsbO, a lumenal PSII subunit known to be disulfide bonded, and a recombinant form of the molecule can introduce a disulfide bond in PsbO in vitro. The documentation of a sulfhydryl-oxidizing activity in the thylakoid lumen further underscores the importance of catalyzed thiol-disulfide chemistry for the biogenesis of the thylakoid compartment.

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“…On the basis of its specific thermostability, acidic isoelectric point, and anomalous electrophoretic mobility, MSP was classified as a "natively unfolded" (7) protein or a "molten globule" (8). Soluble MSP unfolds extremely easily in the presence of 2 M Gdn-HCl or under relatively low pressure (about 160-180 MPa) (9,10). The crystal structure of PSII and studies of pH-induced structural changes in MSP suggested that MSP might provide a pathway for transporting protons from the catalyzing site of oxygen evolution to the lumen (11)(12)(13).…”

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confidence: 99%

Structural and Functional Differentiation of Three Groups of Tyrosine Residues by Acetylation of N-Acetylimidazole in Manganese Stabilizing Protein

et al. 2004

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To study its contribution to the assembly of the green plant manganese stabilizing protein (MSP) into photosystem II (PSII), tyrosine residues were specifically acetylated using N-acetylimidazole (NAI). In soluble MSP, three groups of Tyr residues could be differentiated by NAI acetylation: approximately 5 (actually ∼5.2) Tyr residues could be easily acetylated (superficial), 1-2 Tyr residues could be acetylated when the NAI concentration was sufficiently high (superficially buried), and 1-2 Tyr residues could only be acetylated in the presence of the denaturant, urea (deeply buried). Acetylation of the 5.2 Tyr residues did not affect the reconstitution or oxygen-evolving activities of the MSP, and far-UV circular dichroism (CD) analysis showed that the altered MSP retained most of its native secondary structure. These results suggested that the 5.2 Tyr residues are not absolutely essential to the function of MSP. However, further modification of the 1-2 superficially buried Tyr residues (for a total acetylation of ∼6.4 Tyr residues) completely abrogated the MSP rebinding and oxygen evolution activities. Finally, at least one tyrosine residue was inaccessible to NAI until MSP was completely unfolded by 8 M urea. Deacetylation of MSP with 6.4 or 8 acetylated Tyr residues with hydroxylamine restored most of the rebinding and oxygen-evolving activities. A prominent red shift in fluorescence spectra of MSP (excited at 280 or 295 nm) was observed after modification of 6.4 Tyr residues, and a further shift could be found after all 8 Tyr residues were modified, indicating a great loss of native secondary structure. Far-UV CD revealed that MSP was mostly unfolded when 6.4 Tyr residues were modified and completely unfolded when all 8 Tyr residues were modified. Fluorescence and far-UV CD studies revealed that loss of MSP rebinding to PSII membranes following NAI modification correlated well with conformational changes in MSP. Together, these results indicate that different tyrosine residues have different contributions to the binding and assembly of MSP into PSII.In green plants, photosystem II (PSII) 1 catalyzes the lightdriven reduction of plastoquinone and the oxidation of water to molecular oxygen (1). All major components of PSII required for its activity, including chlorophyll a (P680), tyrosine (Y Z ), pheophytin (Pheo), and the primary (Q A ) and secondary (Q B ) quinone acceptors are located within a heterodimeric matrix consisting of polypeptides D1 and D2. Although the essential pathway for photosynthetic water oxidation into molecular oxygen and protons has been established, a detailed comprehensive picture of water oxidation has not been elucidated to date. In particular, the manganese cluster of the water-oxidizing complex (WOC) is not well understood. Site-directed mutagenesis experiments have revealed that several amino acid residues of D1 and D2 are functionally and/or structurally relevant for establishing a competent WOC. However, other extrinsic polypeptides cannot be excluded as being essen...

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Extrinsic 33-kilodalton protein of spinach oxygen-evolving complexes: kinetic studies of folding and disulfide reduction

Cited by 40 publications

References 30 publications

Intramolecular Cross-linking of the Extrinsic 33-kDa Protein Leads to Loss of Oxygen Evolution but Not Its Ability of Binding to Photosystem II and Stabilization of the Manganese Cluster

Intramolecular Cross-linking of the Extrinsic 33-kDa Protein Leads to Loss of Oxygen Evolution but Not Its Ability of Binding to Photosystem II and Stabilization of the Manganese Cluster

Lumen Thiol Oxidoreductase1, a Disulfide Bond-Forming Catalyst, Is Required for the Assembly of Photosystem II inArabidopsis

Structural and Functional Differentiation of Three Groups of Tyrosine Residues by Acetylation of N-Acetylimidazole in Manganese Stabilizing Protein

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