2BH5

X-ray structure of the M100K variant of ferric cyt c-550 from Paracoccus versutus determined at 295 K.

Summary for 2BH5

• Entry DOI: 10.2210/pdb2bh5/pdb
• Related: 2BGV 2BH4
• Descriptor: CYTOCHROME C-550, HEME C (3 entities in total)
• Functional Keywords: c-type cytochrome, heme, electron transfer, axial ligand, pyrrolidone carboxylic acid
• Biological source: PARACOCCUS VERSUTUS
• Total number of polymer chains: 1
• Total formula weight: 14773.36

Authors

Worrall, J.A.R.,van Roon, A.-M.M.,Ubbink, M.,Canters, G.W. (deposition date: 2005-01-07, release date: 2005-05-11, Last modification date: 2024-10-16)

Primary citation

Worrall, J.A.R.,Van Roon, A.-M.M.,Ubbink, M.,Canters, G.W.
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.
FEBS J., 272:2441-, 2005

PubMed Abstract: The 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.

PubMed: 15885094
DOI: 10.1111/J.1742-4658.2005.04664.X

Experimental method

X-RAY DIFFRACTION (1.95 Å)