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X-ray structure of the M100K variant of ferric cyt c-550 from Paracoccus versutus determined at 295 K.X-ray structure of the M100K variant of ferric cyt c-550 from Paracoccus versutus determined at 295 K.
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of cytochrome c-550 from the nonphotosynthetic bacteria Paraccocus versutus has been solved by X-ray crystallography to 1.90 A resolution, and reveals a high structural homology to other bacterial cytochromes c(2). The effect of replacing the axial heme-iron methionine ligand with a lysine residue on protein structure and unfolding has been assessed using the M100K variant. From X-ray structures at 1.95 and 1.55 A resolution it became clear that the amino group of the lysine side chain coordinates to the heme-iron. Structural differences compared to the wild-type protein are confined to the lysine ligand loop connecting helices four and five. In the heme cavity an additional water molecule is found which participates in an H-bonding interaction with the lysine ligand. Under cryo-conditions extra electron density in the lysine ligand loop is revealed, leading to residues K97 to T101 being modeled with a double main-chain conformation. Upon unfolding, dissociation of the lysine ligand from the heme-iron is shown to be pH dependent, with NMR data consistent with the occurrence of a ligand exchange mechanism similar to that seen for the wild-type protein. The effect of replacing the axial methionine ligand with a lysine residue in cytochrome c-550 from Paracoccus versutus assessed by X-ray crystallography and unfolding.,Worrall JA, van Roon AM, Ubbink M, Canters GW FEBS J. 2005 May;272(10):2441-55. PMID:15885094[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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