Crystal structure determinations of oxidized and reduced pseudoazurins from Achromobacter cycloclastes. Concerted movement of copper site in redox forms with the rearrangement of hydrogen bond at a remote histidine.
The crystal structures of oxidized and reduced pseudoazurins from a denitrifying bacterium, Achromobacter cycloclastes IAM1013, have been determined at 1.35- and 1.6-A resolutions, respectively. The copper site in the oxidized state exhibits a distorted tetrahedral structure like those of other pseudoazurins. However, not only a small change of the copper geometry, but concerted peptide bond flips are identified. The imidazole ring of remote His6 has a hydrogen bonding distance of 2.73 A between N-delta1(His6) and O-gamma1(Thr36) in the oxidized protein. When the protein is reduced at pH 6.0, the imidazole ring rotates by 30.3 degrees and moves 1.00 A away from the position of the oxidized state. A new hydrogen bond between N-epsilon2(His6) and O-epsilon1(Glu4) is formed with a distance of 3.03 A, while the hydrogen bond between N-delta1(His6)-O-gamma1(Thr36) is maintained with an interatomic distance of 2.81 A. A concomitant peptide bond flip of main chain between Ile34 and Thr36 occurs.
Inoue
T
T
Department of Materials Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
Nishio
N
N
Suzuki
S
S
Kataoka
K
K
Kohzuma
T
T
Kai
Y
Y
D000421:Alcaligenes / Q000737:chemistry*; D001400:Azurin / Q000031:analogs & derivatives* / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D001665:Binding Sites; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008667:Metalloproteins / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D001426:Bacterial Proteins; D008667:Metalloproteins; C047163:pseudoazurin; D001400:Azurin; D003300:Copper