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PDBsum entry 1f1f
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Electron transport
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PDB id
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1f1f
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structures of cytochrome c-549 and cytochrome c6 from the cyanobacterium arthrospira maxima.
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Authors
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M.R.Sawaya,
D.W.Krogmann,
A.Serag,
K.K.Ho,
T.O.Yeates,
C.A.Kerfeld.
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Ref.
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Biochemistry, 2001,
40,
9215-9225.
[DOI no: ]
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PubMed id
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Abstract
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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.
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