title: Crystal structure of auracyanin, a "blue" copper protein from the green thermophilic photosynthetic bacterium Chloroflexus aurantiacus.
abstract: Auracyanin B, one of two similar blue copper proteins produced by the thermophilic green non-sulfur photosynthetic bacterium Chloroflexus aurantiacus, crystallizes in space group P6(4)22 (a=b=115.7 A, c=54.6 A). The structure was solved using multiple wavelength anomalous dispersion data recorded about the CuK absorption edge, and was refined at 1.55 A resolution. The molecular model comprises 139 amino acid residues, one Cu, 247 H(2)O molecules, one Cl(-) and two SO(4)(2-). The final residual and estimated standard uncertainties are R=0.198, ESU=0.076 A for atomic coordinates and ESU=0.05 A for Cu---ligand bond lengths, respectively. The auracyanin B molecule has a standard cupredoxin fold. With the exception of an additional N-terminal strand, the molecule is very similar to that of the bacterial cupredoxin, azurin. As in other cupredoxins, one of the Cu ligands lies on strand 4 of the polypeptide, and the other three lie along a large loop between strands 7 and 8. The Cu site geometry is discussed with reference to the amino acid spacing between the latter three ligands. The crystallographically characterized Cu-binding domain of auracyanin B is probably tethered to the periplasmic side of the cytoplasmic membrane by an N-terminal tail that exhibits significant sequence identity with known tethers in several other membrane-associated electron-transfer proteins.
authors.affiliation: Department of Biochemistry, University of Sydney, New South Wales, 2006, Australia.
authors.forename: C S
authors.initials: CS
authors.lastname: Bond
authors.forename: R E
authors.initials: RE
authors.lastname: Blankenship
authors.forename: H C
authors.initials: HC
authors.lastname: Freeman
authors.forename: J M
authors.initials: JM
authors.lastname: Guss
authors.forename: M J
authors.initials: MJ
authors.lastname: Maher
authors.forename: F M
authors.initials: FM
authors.lastname: Selvaraj
authors.forename: M C
authors.initials: MC
authors.lastname: Wilce
authors.forename: K M
authors.initials: KM
authors.lastname: Willingham
mesh_terms: D000595:Amino Acid Sequence; D001400:Azurin / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D019414:Chlorobi / Q000737:chemistry*; D003300:Copper / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D006639:Histidine / Q000378:metabolism; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010970:Plastocyanin / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; C073756:auracyanin A protein, bacteria; C073757:auracyanin B-1 protein, bacteria; C017079:mauC protein, Methylobacterium extorquens; D001400:Azurin; D006639:Histidine; D003300:Copper; D010970:Plastocyanin