Crystal Structure of Auracyanin, a "Blue" Copper Protein from the Green Thermophilic Photosynthetic Bacterium Chloroflexus aurantiacus

Charles S. Bond, Robert E. Blankenship, Hans C. Freeman, J.Mitchell Guss, Megan J. Maher, Fabiyola M. Selvaraj, Matthew C.J. Wilce, Katrina M. Willingham

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38 Citations (Scopus)

Abstract

Auracyanin B, one of two similar blue copper proteins produced by the thermophilic green non-sulfurphotosynthetic bacterium Chloroflexus aurantiacus, crystallizes in space group P 6422(a=b=115.7 Å, c=54.6 Å). The structure was solved usingmultiple wavelength anomalous dispersion data recorded about the Cu K absorption edge, and was refined at1.55 Å resolution. The molecular model comprises 139 amino acid residues, one Cu, 247 H2O molecules, oneCl− and two SO42−. The final residual and estimated standard uncertainties are R=0.198, ESU=0.076 Å for atomic coordinates and ESU=0.05 Å for Cu---ligandbond lengths, respectively. The auracyanin B molecule has a standard cupredoxin fold. With the exception of an additionalN-terminal strand, the molecule is very similar to that of the bacterial cupredoxin, azurin. As in other cupredoxins, one of the Culigands lies on strand 4 of the polypeptide, and the other three lie along a large loop between strands 7 and 8. The Cu sitegeometry is discussed with reference to the amino acid spacing between the latter three ligands. The crystallographicallycharacterized Cu-binding domain of auracyanin B is probably tethered to the periplasmic side of the cytoplasmic membrane by anN-terminal tail that exhibits significant sequence identity with known tethers in several other membrane-associatedelectron-transfer proteins.
Original languageEnglish
Pages (from-to)47-67
JournalJournal of Molecular Biology
Volume306
DOIs
Publication statusPublished - 2001

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