Structural characterization of the nickel-binding properties of Bacillus pasteurii urease accessory protein (Ure)E in solution.
Urease activation is critical to the virulence of many human and animal pathogens. Urease possesses multiple, nickel-containing active sites, and UreE, the only nickel-binding protein among the urease accessory proteins, activates urease by transporting nickel ions. We performed NMR experiments to investigate the solution structure and the nickel-binding properties of Bacillus pasteurii (Bp) UreE. The secondary structures and global folds of BpUreE were determined for its metal-free and nickel-bound forms. The results indicated that no major structural change of BpUreE arises from the nickel binding. In addition to the previously identified nickel-binding site (Gly(97)-Cys(103)), the C-terminal tail region (Lys(141)-His(147)) was confirmed for the first time to be involved in the nickel binding. The C-terminally conserved sequence ((144)GHQH(147)) was confirmed to have an inherent nickel-binding ability. Nickel addition to 1.6 mm subunit, a concentration where BpUreE predominantly forms a tetramer upon the nickel binding, induced a biphasic spectral change consistent with binding of up to at least three nickel ions per tetrameric unit. In contrast, nickel addition to 0.1 mm subunit, a concentration at which the protein is primarily a dimer, caused a monophasic spectral change consistent with more than 1 equivalent per dimeric unit. Combined with the equilibrium dialysis results, which indicated 2.5 nickel equivalents binding per dimer at a micromolar protein concentration, the nickel-binding stoichiometry of BpUreE at a physiological concentration could be three nickel ions per dimer. Altogether, the present results provide the first detailed structural data concerning the nickel-binding properties of intact, wild-type BpUreE in solution.
Won
Hyung-Sik
HS
National Research Laboratory for Membrane Protein Structure, College of Pharmacy, Seoul National University, Seoul 151-742, Korea.
Lee
Yeon-Hee
YH
Kim
Ji-Hun
JH
Shin
In Seon
IS
Lee
Mann Hyung
MH
Lee
Bong-Jin
BJ
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D007477:Ions; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009532:Nickel / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
D001426:Bacterial Proteins; D002352:Carrier Proteins; D007477:Ions; D010455:Peptides; C090404:UreE protein, Bacteria; D009532:Nickel