2c8s
CYTOCHROME CL FROM METHYLOBACTERIUM EXTORQUENS
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OverviewOverview
The structure of cytochrome cL from Methylobacterium extorquens has been, determined by X-ray crystallography to a resolution of 1.6 A. This, unusually large, acidic cytochrome is the physiological electron acceptor, for the quinoprotein methanol dehydrogenase in the periplasm of, methylotrophic bacteria. Its amino acid sequence is completely different, from that of other cytochromes but its X-ray structure reveals a core that, is typical of class I cytochromes c, having alpha-helices folded into a, compact structure enclosing the single haem c prosthetic group and leaving, one edge of the haem exposed. The haem is bound through thioether bonds to, Cys65 and Cys68, and the fifth ligand to the haem iron is provided by, His69. Remarkably, the sixth ligand is provided by His112, and not by, Met109, which had been shown to be the sixth ligand in solution., Cytochrome cL is unusual in having a disulphide bridge that tethers the, long C-terminal extension to the body of the structure. The crystal, structure reveals that, close to the inner haem propionate, there is, tightly bound calcium ion that is likely to be involved in stabilization, of the redox potential, and that may be important in the flow of electrons, from reduced pyrroloquinoline quinone in methanol dehydrogenase to the, haem of cytochrome cL. As predicted, both haem propionates are exposed to, solvent, accounting for the unusual influence of pH on the redox potential, of this cytochrome.
About this StructureAbout this Structure
2C8S is a Single protein structure of sequence from Methylobacterium extorquens with CA and HEM as ligands. This structure superseeds the now removed PDB entry 1UMM. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
The 1.6A X-ray structure of the unusual c-type cytochrome, cytochrome cL, from the methylotrophic bacterium Methylobacterium extorquens., Williams P, Coates L, Mohammed F, Gill R, Erskine P, Bourgeois D, Wood SP, Anthony C, Cooper JB, J Mol Biol. 2006 Mar 17;357(1):151-62. Epub 2006 Jan 5. PMID:16414073
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