5zzn
From Proteopedia
Crystal structure of photosystem II from an SQDG-deficient mutant of Thermosynechococcus elongatus
Structural highlights
Function[PSBL_THEEB] Required for PSII activity (By similarity). [YCF12_THEEB] A core subunit of photosystem II (PSII).[HAMAP-Rule:MF_01329] [PSBB_THEEB] One of the components of the core complex of photosystem II (PSII). It binds chlorophyll and helps catalyze the primary light-induced photochemical processes of PSII. PSII is a light-driven water:plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation.[HAMAP-Rule:MF_01495][1] [2] [3] [PSBA1_THEEB] This is one of the two reaction center proteins of photosystem II. [PSBX_THEEB] Involved in the binding and/or turnover of quinones at the Q(B) site of Photosystem II.[4] [CY550_THEEB] Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II. It is not essential for growth under normal conditions but is required under low CO(2) concentrations.[HAMAP-Rule:MF_01378] [PSBO_THEEB] MSP binds to a putative Mn-binding protein and keeps 2 of the 4 Mn-atoms associated with PSII (By similarity). [PSBF_THEEB] This b-type cytochrome is tightly associated with the reaction center of photosystem II and possibly is part of the water-oxidation complex (By similarity).[HAMAP-Rule:MF_00643] [PSBC_THEEB] One of the components of the core complex of photosystem II (PSII). It binds chlorophyll and helps catalyze the primary light-induced photochemical processes of PSII. PSII is a light-driven water:plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation.[HAMAP-Rule:MF_01496][5] [6] [7] [PSBJ_THEEB] This protein is a component of the reaction center of photosystem II (By similarity). [PSBT_THEEB] Seems to play a role in the dimerization of PSII.[8] [PSBU_THEEB] Stabilizes the structure of photosystem II oxygen-evolving complex (OEC), the ion environment of oxygen evolution and protects the OEC against heat-induced inactivation (By similarity).[HAMAP-Rule:MF_00589] [PSBI_THEEB] This protein is a component of the reaction center of photosystem II.[HAMAP-Rule:MF_01316] [PSBZ_THEEB] Controls the interaction of photosystem II (PSII) cores with the light-harvesting antenna. May also aid in binding of PsbK, Ycf12 and the oxygen-evolving complex to PSII, at least in vitro.[9] [PSBK_THEEB] This protein is a component of the reaction center of photosystem II.[HAMAP-Rule:MF_00441] [PSBE_THEEB] This b-type cytochrome is tightly associated with the reaction center of photosystem II and possibly is part of the water-oxidation complex.[HAMAP-Rule:MF_00642] Publication Abstract from PubMedSulfoquinovosyl-diacylglycerol (SQDG) is one of the four lipids present in the thylakoid membranes. Depletion of SQDG causes different degrees of effects on photosynthetic growth and activities in different organisms. Four SQDG molecules bind to each monomer of the photosystem II (PSII), but their role in PSII function has not been characterized in detail, and no PSII structure without SQDG has been reported. We analyzed the activities of PSII from an SQDG-deficient mutant of the cyanobacterium Thermosynechococcus elongatus by various spectroscopic methods, which showed that depletion of SQDG partially impaired the PSII activity by impairing secondary quinone (QB) exchange at the acceptor site. We further solved the crystal structure of the PSII dimer from the SQDG deletion mutant at 2.1 A resolution, and found that all of the four SQDG-binding sites were occupied by other lipids, most likely PG molecules. Replacement of SQDG at a site near the head of QB provides a possible explanation for the QB impairment. The replacement of two SQDGs located at the monomer-monomer interface by other lipids decreased the stability of PSII dimer, resulting in an increase in the amount of PSII monomer in the mutant. The present results thus suggest that while SQDG binding in all of the PSII biding sites is necessary to fully maintain the activity and stability of PSII, replacement of SQDG by other lipids can partially compensate for their functions. Thylakoid membrane lipid sulfoquinovosyl-diacylglycerol (SQDG) is required for full functioning of photosystem II in Thermosynechococcus elongatus.,Nakajima Y, Umena Y, Nagao R, Endo K, Kobayashi K, Akita F, Suga M, Wada H, Noguchi T, Shen JR J Biol Chem. 2018 Aug 3. pii: RA118.004304. doi: 10.1074/jbc.RA118.004304. PMID:30076221[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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