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Title: Mass spectrometry-based cross-linking study shows that the Psb28 protein binds to cytochrome b 559 in Photosystem II

Photosystem II (PSII), a large pigment protein complex, undergoes rapid turnover under natural conditions. During assembly of PSII, oxidative damage to vulnerable assembly intermediate complexes must be prevented. Psb28, the only cytoplasmic extrinsic protein in PSII, protects the RC47 assembly intermediate of PSII and assists its efficient conversion into functional PSII. Its role is particularly important under stress conditions when PSII damage occurs frequently. Psb28 is not found, however, in any PSII crystal structure, and its structural location has remained unknown. Here in this study, we used chemical cross-linking combined with mass spectrometry to capture the transient interaction of Psb28 with PSII. We detected three cross-links between Psb28 and the α- and β-subunits of cytochrome b 559, an essential component of the PSII reaction-center complex. These distance restraints enable us to position Psb28 on the cytosolic surface of PSII directly above cytochrome b559, in close proximity to the QB site. Protein–protein docking results also support Psb28 binding in this region. Determination of the Psb28 binding site and other biochemical evidence allow us to propose a mechanism by which Psb28 exerts its protective effect on the RC47 intermediate. This study also shows that isotope-encoded cross-linking with the “mass tags” selection criteriamore » allows confident identification of more cross-linked peptides in PSII than has been previously reported. Finally, this approach thus holds promise to identify other transient protein–protein interactions in membrane protein complexes.« less
 [1] ;  [2] ;  [3] ;  [4] ; ORCiD logo [4] ;  [3] ;  [2]
  1. Washington Univ., St. Louis, MO (United States). Dept. of Biology and Dept. of Chemistry
  2. Washington Univ., St. Louis, MO (United States). Dept. of Biology
  3. Washington Univ., St. Louis, MO (United States). Dept. of Chemistry
  4. Univ. of Illinois, Urbana-Champaign, IL (United States). Beckman Inst. for Advanced Science and Technology, Dept. of Biochemistry
Publication Date:
Grant/Contract Number:
SC0001035; 2P41GM103422; MCB0745611; U54-GM087519; P41-GM104601
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 9; Related Information: PARC partners with Washington University in St. Louis (lead); University of California, Riverside; University of Glasgow, UK; Los Alamos National Laboratory; University of New Mexico; New Mexico Corsortium; North Carolina State University; Northwestern University; Oak Ridge National Laboratory; University of Pennsylvania; Sandia National Laboratories; University of Sheffield, UK; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Energy Frontier Research Centers (EFRC) (United States). Photosynthetic Antenna Research Center (PARC)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institutes of Health (NIH); National Science Foundation (NSF)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; cyanobacteria; photosynthesis; membrane protein; Photosystem II; chemical cross-linking
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1388595