1f1c
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CRYSTAL STRUCTURE OF CYTOCHROME C549
OverviewOverview
Cytochrome c(6) and cytochrome c-549 are small (89 and 130 amino acids, respectively) monoheme cytochromes that function in photosynthesis. They, appear to have descended relatively recently from the same ancestral gene, but have diverged to carry out very different functional roles, underscored by the large difference between their midpoint potentials of, nearly 600 mV. We have determined the X-ray crystal structures of both, proteins isolated from the cyanobacterium Arthrospira maxima. The two, structures are remarkably similar, superimposing on backbone atoms with an, rmsd of 0.7 A. Comparison of the two structures suggests that differences, in solvent exposure of the heme and the electrostatic environment of the, heme propionates, as well as in heme iron ligation, are the main, determinants of midpoint potential in the two proteins. In addition, the, crystal packing of both A. maxima cytochrome c-549 and cytochrome c(6), suggests that the proteins oligomerize. Finally, the cytochrome c-549, dimer we observe can be readily fit into the recently described model of, cyanobacterial photosystem II.
About this StructureAbout this Structure
1F1C is a Single protein structure of sequence from Arthrospira maxima with HEM as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Structures of cytochrome c-549 and cytochrome c6 from the cyanobacterium Arthrospira maxima., Sawaya MR, Krogmann DW, Serag A, Ho KK, Yeates TO, Kerfeld CA, Biochemistry. 2001 Aug 7;40(31):9215-25. PMID:11478889
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