TY - JOUR
T1 - Psb27, a transiently associated protein, binds to the chlorophyll binding protein CP43 in photosystem II assembly intermediates
AU - Liu, Haijun
AU - Huang, Richard Y.C.
AU - Chen, Jiawei
AU - Gross, Michael L.
AU - Pakrasi, Himadri B.
PY - 2011/11/8
Y1 - 2011/11/8
N2 - Photosystem II (PSII), a large multisubunit pigment-protein complex localized in the thylakoid membrane of cyanobacteria and chloroplasts, mediates light-driven evolution of oxygen from water. Recently, a high-resolution X-ray structure of the mature PSII complex has become available. Two PSII polypeptides, D1 and CP43, provide many of the ligands to an inorganic Mn 4Ca center that is essential for water oxidation. Because of its unusual redox chemistry, PSII often undergoes degradation followed by stepwise assembly. Psb27, a small luminal polypeptide, functions as an important accessory factor in this elaborate assembly pathway. However, the structural location of Psb27 within PSII assembly intermediates has remained elusive. Here we report that Psb27 binds to CP43 in such assembly intermediates. We treated purified genetically tagged PSII assembly intermediate complexes from the cyanobacterium Synechocystis 6803 with chemical cross-linkers to examine intermolecular interactions between Psb27 and various PSII proteins. First, the water-soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was used to cross-link proteins with complementary charged groups in close association to one another. In the His27ΔctpAPSII preparation, a 58-kDa cross-linked species containing Psb27 and CP43 was identified. This species was not formed in the HT3ΔctpAΔpsb27PSII complex in which Psb27 was absent. Second, the homobifunctional thiol-cleavable cross-linker 3,3′- dithiobis(sulfosuccinimidylpropionate) (DTSSP) was used to reversibly cross-link Psb27 to CP43 in His27ΔctpAPSII preparations, which allowed the use of liquid chromatography/tandem MS to map the cross-linking sites as Psb27K 63↔CP43D 321 (trypsin) and CP43K 215↔ Psb27D 58AGGLK 63↔CP43D 321 (chymotrypsin), respectively. Our data suggest that Psb27 acts as an important regulatory protein during PSII assembly through specific interactionswith the luminal domain of CP43.
AB - Photosystem II (PSII), a large multisubunit pigment-protein complex localized in the thylakoid membrane of cyanobacteria and chloroplasts, mediates light-driven evolution of oxygen from water. Recently, a high-resolution X-ray structure of the mature PSII complex has become available. Two PSII polypeptides, D1 and CP43, provide many of the ligands to an inorganic Mn 4Ca center that is essential for water oxidation. Because of its unusual redox chemistry, PSII often undergoes degradation followed by stepwise assembly. Psb27, a small luminal polypeptide, functions as an important accessory factor in this elaborate assembly pathway. However, the structural location of Psb27 within PSII assembly intermediates has remained elusive. Here we report that Psb27 binds to CP43 in such assembly intermediates. We treated purified genetically tagged PSII assembly intermediate complexes from the cyanobacterium Synechocystis 6803 with chemical cross-linkers to examine intermolecular interactions between Psb27 and various PSII proteins. First, the water-soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was used to cross-link proteins with complementary charged groups in close association to one another. In the His27ΔctpAPSII preparation, a 58-kDa cross-linked species containing Psb27 and CP43 was identified. This species was not formed in the HT3ΔctpAΔpsb27PSII complex in which Psb27 was absent. Second, the homobifunctional thiol-cleavable cross-linker 3,3′- dithiobis(sulfosuccinimidylpropionate) (DTSSP) was used to reversibly cross-link Psb27 to CP43 in His27ΔctpAPSII preparations, which allowed the use of liquid chromatography/tandem MS to map the cross-linking sites as Psb27K 63↔CP43D 321 (trypsin) and CP43K 215↔ Psb27D 58AGGLK 63↔CP43D 321 (chymotrypsin), respectively. Our data suggest that Psb27 acts as an important regulatory protein during PSII assembly through specific interactionswith the luminal domain of CP43.
KW - Mass spectrometry
KW - Photosynthesis
KW - Protein structure
UR - http://www.scopus.com/inward/record.url?scp=81055130048&partnerID=8YFLogxK
U2 - 10.1073/pnas.1111597108
DO - 10.1073/pnas.1111597108
M3 - Article
C2 - 22031695
AN - SCOPUS:81055130048
SN - 0027-8424
VL - 108
SP - 18536
EP - 18541
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 45
ER -