Structural and functional characterization of the Geobacillus copper nitrite reductase: involvement of the unique N-terminal region in the interprotein electron transfer with its redox partner.
The crystal structures of copper-containing nitrite reductase (CuNiR) from the thermophilic Gram-positive bacterium Geobacillus kaustophilus HTA426 and the amino (N)-terminal 68 residue-deleted mutant were determined at resolutions of 1.3Å and 1.8Å, respectively. Both structures show a striking resemblance with the overall structure of the well-known CuNiRs composed of two Greek key β-barrel domains; however, a remarkable structural difference was found in the N-terminal region. The unique region has one β-strand and one α-helix extended to the northern surface of the type-1 copper site. The superposition of the Geobacillus CuNiR model on the electron-transfer complex structure of CuNiR with the redox partner cytochrome c551 in other denitrifier system led us to infer that this region contributes to the transient binding with the partner protein during the interprotein electron transfer reaction in the Geobacillus system. Furthermore, electron-transfer kinetics experiments using N-terminal residue-deleted mutant and the redox partner, Geobacillus cytochrome c551, were carried out. These structural and kinetics studies demonstrate that the region is directly involved in the specific partner recognition.
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; Department of Materials Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan; Molecular Biology Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
Yohta
Y
Fukuda
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
Hiroyasu
H
Koteishi
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
Ryohei
R
Yoneda
Molecular Biology Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
Taro
T
Tamada
Microbial Genome Research Group, Japan Agency of Marine-Earth Science and Technology, Yokosuka, Kanagawa 237-0061, Japan.
Hideto
H
Takami
Department of Materials Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
Tsuyoshi
T
Inoue
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan. Electronic address: nojiri@ch.wani.osaka-u.ac.jp.
Masaki
M
Nojiri
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D020134:Catalytic Domain; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000235:genetics; D056506:Geobacillus / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009572:Nitrite Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D003300:Copper; C017167:cytochrome C(551); D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing
Copper nitrite reductase; Cytochrome c; Denitrification; Electron transfer; X-ray crystallography