Structural basis for Ni(2+) transport and assembly of the urease active site by the metallochaperone UreE from Bacillus pasteurii.
Bacillus pasteurii UreE (BpUreE) is a putative chaperone assisting the insertion of Ni(2+) ions in the active site of urease. The x-ray structure of the protein has been determined for two crystal forms, at 1.7 and 1.85 A resolution, using SIRAS phases derived from a Hg(2+)-derivative. BpUreE is composed of distinct N- and C-terminal domains, connected by a short flexible linker. The structure reveals the topology of an elongated homodimer, formed by interaction of the two C-terminal domains through hydrophobic interactions. A single Zn(2+) ion bound to four conserved His-100 residues, one from each monomer, connects two dimers resulting in a tetrameric BpUreE known to be formed in concentrated solutions. The Zn(2+) ion can be replaced by Ni(2+) as shown by anomalous difference maps obtained on a crystal of BpUreE soaked in a solution containing NiCl(2). A large hydrophobic patch surrounding the metal ion site is surface-exposed in the biologically relevant dimer. The BpUreE structure represents the first for this class of proteins and suggests a possible role for UreE in the urease nickel-center assembly.
Remaut
H
H
Laboratory of Protein Biochemistry and Protein Engineering, Ghent University, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Safarov
N
N
Ciurli
S
S
Van Beeumen
J
J
D001407:Bacillus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D017136:Ion Transport; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D009532:Nickel / Q000378:metabolism*; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D014510:Urease / Q000737:chemistry* / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry
D001426:Bacterial Proteins; D002352:Carrier Proteins; D018832:Molecular Chaperones; C090404:UreE protein, Bacteria; D009532:Nickel; D014510:Urease; D015032:Zinc