Analysis of pH-Induced Structural Changes of the Isolated Extrinsic 33 Kilodalton Protein of Photosystem II

Shutova, Tatiana; Irrgang, Klaus−Dieter; Shubin, Vladimir; Klimov, Vyacheslav V.; Ренгер, Г.

doi:10.1021/bi963115h

Cited by 76 publications

(109 citation statements)

References 56 publications

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“…Thus, the major secondary structure of MSP remains unaffected at pH 4. Moreover, our data are consistent with the results that the secondary structure elements of MSP remained constant upon decrease of pH from 6.8 to 3.8 (27). However, notably, the decrease of pH from 6 to 4 induced a trivial spectral change around 220 nm, indicating a slight state transition, although both are ordered states (see the Discussion below).…”

Section: Evidence For the Existence Of Different Msp Conformationasupporting

confidence: 92%

pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II

et al. 2004

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In this paper, we analyzed the pH-induced changes in the conformational states of the manganese-stabilizing protein (MSP) of photosystem II. Distinct conformational states of MSP were identified using fluorescence spectra, far-UV circular dichroism, and pressure-induced unfolding at varying suspension pH values, and four different conformational states of MSP were clearly distinguished using the center of fluorescence spectra mass when suspension pH was altered from 2 to 12. MSP was completely unfolded at a suspension pH above 11 and partly unfolded below a pH of 3. Analysis of the center of fluorescence spectral mass showed that the MSP structure appears stably folded around pH 6 and 4. The conformational state of MSP at pH 4 seems more stable than that at pH 6. Studies of peak positions of tryptophan fluorescence and MSP-bound 1-anilinonaphthalene-8-sulfonic acid fluorescence spectra supported this observation. A decrease in the suspension pH to 2 resulted in significant alterations in the MSP structure possibly because of protonation of unprotonated residues at lower pH, suggesting the existence of a large number of unprotonated amino acid residues at neutral pH possibly useful for proton transport in oxygen evolution. The acidic pH-induced conformational changes of MSP were reversible upon increase of pH to neutral pH; however, N-bromosuccinimide modification of tryptophan (Trp241) blocks the recovery of pH-induced conformational changes in MSP, implying that Trp241 is a key residue for the unfolded protein to form a functional structure. Thus, pH-induced structural changes of stable MSP (pH 6-4) may be utilized to analyze its functionality as a cofactor for oxygen evolution.Photosystem II (PSII) 1 catalyzes the light-driven reduction of plastoquinone and oxidation of water to molecular oxygen (1). The major components of PSII required for its activity include chlorophyll a (P680), tyrosine residue (Y Z ), pheophytin (Pheo), and primary (Q A ) and secondary (Q B ) quinone acceptors; all of them are located within a heterodimeric matrix consisting of polypeptides D1 and D2. Although the essential pattern of photosynthetic water oxidation into molecular oxygen and protons has been established firmly, a detailed comprehensive picture of water oxidation is still far from a satisfying description. This is especially true for the manganese cluster of the water-oxidizing complex (WOC). Site-directed mutagenesis experiments have revealed that several amino acid residues of D1 and D2 are of functional and/or structural relevance in establishing a competent WOC. However, other polypeptides cannot be excluded for their potential to be essential constituents of WOC (2).Among the proteins that function in PSII oxygen evolution, the extrinsic 33 kDa manganese-stabilizing protein (MSP) has special significance, because it stabilizes the manganese cluster under physiological conditions. The removal of this protein from PSII membranes results in the loss of two Mn 2+ ions and a significant decrease in oxygen evolut...

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Section: Evidence For the Existence Of Different Msp Conformationasupporting

confidence: 92%

pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II

et al. 2004

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“…In addition, reconstitution, oxygen evolution, fluorescence, and far-UV CD data showed that MSP treated with 8 M urea could be restored to the control values by extensive dialysis. Interestingly, the conformational changes shown by the CD spectra ( Figure 5) of MSP modified by 10 mM NAI, 20 mM NAI, and 10 mM NAI/8 M urea were similar to those observed under conditions of varying medium pHs and environmental temperatures (12,13,32).…”

Section: Resultssupporting

confidence: 60%

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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“…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: 71%

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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Analysis of pH-Induced Structural Changes of the Isolated Extrinsic 33 Kilodalton Protein of Photosystem II

Cited by 76 publications

References 56 publications

pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II

pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II

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

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

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