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

Jun Weng, Cuiyan Tan, Jian-Ren Shen, Yong Yu, Xiaomei Zeng, Chunhe Xu, Kangcheng Ruan

Research output: Contribution to journalArticle

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Abstract

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.

Original languageEnglish
Pages (from-to)4855-4861
Number of pages7
JournalBiochemistry
Volume43
Issue number16
DOIs
Publication statusPublished - Apr 27 2004

Fingerprint

Manganese
Proteins
Fluorescence
Suspensions
Tryptophan
photosystem II manganese-stabilizing protein
Bromosuccinimide
Oxygen
Protonation
Dichroism
Protons
Protein Unfolding
Circular Dichroism
Amino Acids
Recovery

ASJC Scopus subject areas

  • Biochemistry

Cite this

pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II. / Weng, Jun; Tan, Cuiyan; Shen, Jian-Ren; Yu, Yong; Zeng, Xiaomei; Xu, Chunhe; Ruan, Kangcheng.

In: Biochemistry, Vol. 43, No. 16, 27.04.2004, p. 4855-4861.

Research output: Contribution to journalArticle

Weng, Jun ; Tan, Cuiyan ; Shen, Jian-Ren ; Yu, Yong ; Zeng, Xiaomei ; Xu, Chunhe ; Ruan, Kangcheng. / pH-Induced Conformational Changes in the Soluble Manganese-Stabilizing Protein of Photosystem II. In: Biochemistry. 2004 ; Vol. 43, No. 16. pp. 4855-4861.
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