5H2F

Crystal structure of the PsbM-deletion mutant of photosystem II

Summary for 5H2F

• Entry DOI: 10.2210/pdb5h2f/pdb
• Descriptor: Photosystem II protein D1 1, Photosystem II reaction center protein K, Photosystem II reaction center protein L, ... (40 entities in total)
• Functional Keywords: photosynthesis, photosystem ii, mutant, psbm
• Biological source: Thermosynechococcus elongatus (strain BP-1); More
• Total number of polymer chains: 36
• Total formula weight: 714040.50

Authors

Uto, S.,Kawakami, K.,Umena, Y.,Iwai, M.,Ikeuchi, M.,Shen, J.R.,Kamiya, N. (deposition date: 2016-10-15, release date: 2017-03-22, Last modification date: 2024-10-23)

Primary citation

Uto, S.,Kawakami, K.,Umena, Y.,Iwai, M.,Ikeuchi, M.,Shen, J.R.,Kamiya, N.
Mutual relationships between structural and functional changes in a PsbM-deletion mutant of photosystem II.
Faraday Discuss., 198:107-120, 2017

PubMed Abstract: Photosystem II (PSII) is a membrane protein complex that performs light-induced electron transfer and oxygen evolution from water. PSII consists of 19 or 20 subunits in its crystal form and binds various cofactors such as chlorophyll a, plastoquinone, carotenoid, and lipids. After initial light excitation, the charge separation produces an electron, which is transferred to a plastoquinone molecule (Q) and then to another plastoquinone (Q). PsbM is a low-molecular-weight subunit with one transmembrane helix, and is located in the monomer-monomer interface of the PSII dimer. The function of PsbM has been reported to be stabilization of the PSII dimer and maintenance of electron transfer efficiency of PSII based on previous X-ray crystal structure analysis at a resolution of 4.2 Å. In order to elucidate the structure-function relationships of PsbM in detail, we improved the quality of PSII crystals from a PsbM-deleted mutant (ΔPsbM-PSII) of Thermosynechococcus elongatus, and succeeded in improving the diffraction quality to a resolution of 2.2 Å. X-ray crystal structure analysis of ΔPsbM-PSII showed that electron densities for the PsbM subunit and neighboring carotenoid and detergent molecules were absent in the monomer-monomer interface. The overall structure of ΔPsbM-PSII was similar to wild-type PSII, but the arrangement of the hydrophobic transmembrane subunits was significantly changed by the deletion of PsbM, resulting in a slight widening of the lipid hole involving Q. The lipid hole-widening further induced structural changes of the bicarbonate ion coordinated to the non-heme Fe(ii) atom and destabilized the polypeptide chains around the Q binding site located far from the position of PsbM. The fluorescence decay measurement indicated that the electron transfer rate from Q to Q was decreased in ΔPsbM-PSII compared with wild-type PSII. The functional change in electron transfer efficiency was fully interpreted based on structural changes caused by the deletion of the PsbM subunit.

PubMed: 28272640
DOI: 10.1039/c6fd00213g

Experimental method

X-RAY DIFFRACTION (2.2 Å)