title: Crystal structure of C-terminal desundecapeptide nitrite reductase from Achromobacter cycloclastes.
abstract: Monoclinic crystal structure of C-terminal desundecapeptide nitrite reductase (NiRc-11) from Achromobacter cycloclastes was determined at 2.6A. NiRc-11 exists as a loose trimer in the crystal. Deletion of 11 residues eliminates all intersubunit hydrogen bonds mediated by the C-terminal tail. The rigid irregular coil 105-112, which constitutes part of the sidewall of the active site pocket, undergoes conformational changes and becomes highly flexible in NiRc-11. Correspondingly, the linker segments between the two copper sites 95-100 and 135-136 are partly relaxed in conformation, which leads to disrupted active site microenvironments responsible for the activity loss and spectral change of NiRc-11. Comparison with the native structure revealed a bulky residue Met331 fastened by hydrogen bonding, which may play a direct role in keeping the right copper site geometry by protruding its side chain against the irregular coil 105-112. Sequence alignment showed that the bulky residue is conserved at position 331, indicating an equal importance of C-terminal segment in other copper-containing nitrite reductases.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15th Datun Road, Chaoyang District, Beijing 100101, China.
authors.forename: Hai-Tao
authors.initials: HT
authors.lastname: Li
authors.forename: Tschining
authors.initials: T
authors.lastname: Chang
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
authors.forename: Chung-Jung
authors.initials: CJ
authors.lastname: Chen
authors.forename: Ming-Yih
authors.initials: MY
authors.lastname: Liu
authors.forename: Lu-Lu
authors.initials: LL
authors.lastname: Gui
authors.forename: Ji-Ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: An
authors.forename: Wen-Rui
authors.initials: WR
authors.lastname: Chang
mesh_terms: D042422:Achromobacter cycloclastes / Q000201:enzymology; D000595:Amino Acid Sequence; D001665:Binding Sites; D003300:Copper / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009532:Nickel / Q000737:chemistry; D009572:Nitrite Reductases / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010446:Peptide Fragments; D003300:Copper; D009532:Nickel; D009572:Nitrite Reductases