1foc
From Proteopedia
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Cytochrome C557: improperly folded thermus thermophilus C552
Overview
Cytochrome rC(557) is an improperly matured, dimeric cytochrome c obtained, from expression of the "signal peptide-lacking" Thermus thermophilus cycA, gene in the cytoplasm of Escherichia coli. It is characterized by its, Q(00) (or alpha-) optical absorption band at 557 nm in the reduced form, (Keightley, J. A., Sanders, D., Todaro, T. R., Pastuszyn, A., and Fee, J., A. (1998) J. Biol. Chem. 273, 12006-12016). We report results of a broad, ranging, biochemical and spectral characterization of this protein that, reveals the presence of a free vinyl group on the porphyrin and a, disulfide bond between the protomers and supports His-Met ligation in both, valence states of the iron. A 3-A resolution x-ray structure shows that, in comparison with the native protein, the heme moiety is rotated 180, degrees about its alpha,gamma-axis; cysteine 14 has formed a thioether, bond with the 2-vinyl of pyrrole ring I instead of the 4-vinyl of pyrrole, ring II, as occurs in the native protein; and a cysteine 11 from each, protomer has formed an intermolecular disulfide bond. Numerous, minor, perturbations exist within the structure of rC(557) in comparison with, that of native protein, which result from heme inversion and, protein-protein interactions across the dimer interface. The unusual, spectral properties of rC(557) are rationalized in terms of this, structure.
About this Structure
1FOC is a Single protein structure of sequence from Thermus thermophilus with HEM as ligand. Full crystallographic information is available from OCA.
Reference
Recombinant cytochrome rC557 obtained from Escherichia coli cells expressing a truncated Thermus thermophilus cycA gene. Heme inversion in an improperly matured protein., McRee DE, Williams PA, Sridhar V, Pastuszyn A, Bren KL, Patel KM, Chen Y, Todaro TR, Sanders D, Luna E, Fee JA, J Biol Chem. 2001 Mar 2;276(9):6537-44. Epub 2000 Nov 7. PMID:11069913
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