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Crystal Structure of Cytochrome c550 from Thermosynechococcus elongatus
Structural highlights
FunctionCY550_THEVB One of the extrinsic, lumenal subunits of photosystem II (PSII). PSII is a light-driven water plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating a proton gradient subsequently used for ATP formation. The extrinsic proteins stabilize the structure of photosystem II oxygen-evolving complex (OEC), the ion environment of oxygen evolution and protect the OEC against heat-induced inactivation. Low-potential cytochrome c that plays a role in the OEC of PSII.[HAMAP-Rule:MF_01378][1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFirst, the crystal structure of cytochrome c-550 (the psbV1 gene product) from the thermophilic cyanobacterium Thermosynechococcus elongatus has been determined to a resolution of 1.8 A. A comparison of the T. elongatus cytochrome c-550 structure to its counterparts from mesophilic organisms, Synechocystis 6803 and Arthrospira maxima, suggests that increased numbers of hydrogen bonds may play a role in the structural basis of thermostability. The cytochrome c-550 in T. elongatus also differs from that in Synechocystis 6803 and Arthrospira maxima in its lack of dimerization and the presence of a trigonal planar molecule, possibly bicarbonate, tightly bound to the heme propionate oxygen atoms. Cytochromes c-550 from T. elongatus, Synechocystis 6803 and Arthrospira maxima exhibit different EPR spectra. A correlation has been done between the heme-axial ligands geometries and the rhombicity calculated from the EPR spectra. This correlation indicates that binding of cytochrome c-550 to Photosystem II is accompanied by structural changes in the heme vicinity. Second, the psbV2 gene product has been found and purified. The UV-visible, EPR and Raman spectra are reported. From the spectroscopic data and from a theoretical structural model based on the cytochrome c-550 structure it is proposed that the 6th ligand of the heme-iron is the Tyr86. Structural and EPR characterization of the soluble form of cytochrome c-550 and of the psbV2 gene product from the cyanobacterium Thermosynechococcus elongatus.,Kerfeld CA, Sawaya MR, Bottin H, Tran KT, Sugiura M, Cascio D, Desbois A, Yeates TO, Kirilovsky D, Boussac A Plant Cell Physiol. 2003 Jul;44(7):697-706. PMID:12881497[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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