title: New molecular packing in a crystal of pseudoazurin from Alcaligenes faecalis: a double-helical arrangement of blue copper.
abstract: Pseudoazurin from the denitrifying bacterium Alcaligenes faecalis (AfPAz) is a blue copper protein and functions as an electron donor to copper-containing nitrite reductase (CuNIR). Conventionally, AfPAz has been crystallized using highly concentrated ammonium sulfate as a precipitant. Here, a needle-like crystal of AfPAz grown in a solution containing a macromolecular precipitant, polyethylene glycol 8000 (PEG 8000), is reported. The crystal belonged to space group P61, with unit-cell parameters a = b = 68.7, c = 94.2 Å. The structure has been determined and refined at 2.6 Å resolution. The asymmetric unit contained two AfPAz molecules contacting each other on negatively charged surfaces. The molecular packing of the crystal showed a right-handed double-helical arrangement of AfPAz molecules and hence of blue copper sites. This structure provides insight into the excluded-volume effect of PEG and the manner of assembly of AfPAz.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Yohta
authors.initials: Y
authors.lastname: Fukuda
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Mizohata
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Inoue
mesh_terms: D042481:Alcaligenes faecalis / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001400:Azurin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002413:Cations, Divalent; D011232:Chemical Precipitation; D003001:Cloning, Molecular; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008667:Metalloproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D008667:Metalloproteins; D011994:Recombinant Proteins; C047163:pseudoazurin; D001400:Azurin; D011092:Polyethylene Glycols; D003300:Copper; C000595216:polyethylene glycol 8000
keywords: Alcaligenes faecalis; blue copper protein; macromolecular crowding effect; molecular packing; pseudoazurin