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Publication Abstract from PubMed

First, 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^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.