title: A 2.0-A structure of the blue copper protein (cupredoxin) from Alcaligenes faecalis S-6.
abstract: The structure of a blue copper protein, cupredoxin, from the potent denitrifying bacterium Alcaligenes faecalis S-6, has been determined and refined against 2 A x-ray diffraction data. The agreement between observed and calculated structure factors is 0.159, and estimated errors in coordinates are 0.09-0.15 A. The protein folds in a beta sandwich similar to plastocyanin and azurin and includes features such as a "kink" and a "tyrosine loop" which have been noted previously for these proteins as well as immunoglobulins. The copper is bound by four ligands, in a distorted tetrahedral arrangement, with Cu-S gamma = 2.07 A (Cys-78), Cu-N delta 1 = 2.10 and 2.21 for His-40 and His-81, and Cu-S delta = 2.69 A (Met-86). Two of the ligands are further oriented by hydrogen bonds either to other side chains (Asn-9 to His-40), backbone atoms (NH...S) or a water molecule (to His-40). The methionine ligand has no extra constraints. The C-terminal loop containing three of the ligands is hydrogen-bonded to the strand containing His-40 by hydrogen bonds between the conserved residues Thr-79 and Asn-41. The pronounced dichroism of the crystal is a result of the orientation of the normal to the C beta-S gamma-Cu plane parallel to the crystallographic 6-fold axis.
authors.affiliation: Department of Biological Structure, University of Washington, Seattle 98115.
authors.forename: E T
authors.initials: ET
authors.lastname: Adman
authors.forename: S
authors.initials: S
authors.lastname: Turley
authors.forename: R
authors.initials: R
authors.lastname: Bramson
authors.forename: K
authors.initials: K
authors.lastname: Petratos
authors.forename: D
authors.initials: D
authors.lastname: Banner
authors.forename: D
authors.initials: D
authors.lastname: Tsernoglou
authors.forename: T
authors.initials: T
authors.lastname: Beppu
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000421:Alcaligenes / Q000378:metabolism*; D001426:Bacterial Proteins; D003198:Computer Simulation; D008024:Ligands; D046911:Macromolecular Substances; D008667:Metalloproteins; D008958:Models, Molecular; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D046911:Macromolecular Substances; D008667:Metalloproteins; C017079:mauC protein, Methylobacterium extorquens