Background: Urease catalyzes the hydrolysis of urea, the final step of organic nitrogen mineralization, using a bimetallic nickel centre. The role of the active site metal ions and amino acid residues has not been elucidated to date. Many pathologies are associated with the activity of ureolytic bacteria, and the efficiency of soil nitrogen fertilization with urea is severely decreased by urease activity. Therefore, the development of urease inhibitors would lead to a reduction of environmental pollution, to enhanced efficiency of nitrogen uptake by plants, and to improved therapeutic strategies for treatment of infections due to ureolytic bacteria. Structure-based design of urease inhibitors would require knowledge of the enzyme mechanism at the molecular level. Results: The structures of native and inhibited urease from Bacillus pasteurii have been determined at a resolution of 2.0 Angstrom by synchrotron X-ray cryogenic crystallography. In the native enzyme, the coordination sphere of each of the two nickel ions is completed by a water molecule and a bridging hydroxide. A fourth water molecule completes a tetrahedral cluster of solvent molecules. The enzyme crystallized in the presence of phenylphosphorodiamidate contains the tetrahedral transition-state analogue diamidophosphoric acid, bound to the two nickel ions in an unprecedented mode. Comparison of the native and inhibited structures reveals two distinct conformations of the flap lining the active-site cavity. Conclusions: The mode of binding of the inhibitor, and a comparison between the native and inhibited urease structures, indicate a novel mechanism for enzymatic urea hydrolysis which reconciles the available structural and biochemical data.

Benini, S., Rypniewski, W.R., Wilson, K.S., Miletti, S., Ciurli, S., Mangani, S. (1999). A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacillus pasteurii: why urea hydrolysis casts two nickels. STRUCTURE, 7(2), 205-216 [10.1016/S0969-2126(99)80026-4].

A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacillus pasteurii: why urea hydrolysis casts two nickels

Mangani, Stefano
1999-01-01

Abstract

Background: Urease catalyzes the hydrolysis of urea, the final step of organic nitrogen mineralization, using a bimetallic nickel centre. The role of the active site metal ions and amino acid residues has not been elucidated to date. Many pathologies are associated with the activity of ureolytic bacteria, and the efficiency of soil nitrogen fertilization with urea is severely decreased by urease activity. Therefore, the development of urease inhibitors would lead to a reduction of environmental pollution, to enhanced efficiency of nitrogen uptake by plants, and to improved therapeutic strategies for treatment of infections due to ureolytic bacteria. Structure-based design of urease inhibitors would require knowledge of the enzyme mechanism at the molecular level. Results: The structures of native and inhibited urease from Bacillus pasteurii have been determined at a resolution of 2.0 Angstrom by synchrotron X-ray cryogenic crystallography. In the native enzyme, the coordination sphere of each of the two nickel ions is completed by a water molecule and a bridging hydroxide. A fourth water molecule completes a tetrahedral cluster of solvent molecules. The enzyme crystallized in the presence of phenylphosphorodiamidate contains the tetrahedral transition-state analogue diamidophosphoric acid, bound to the two nickel ions in an unprecedented mode. Comparison of the native and inhibited structures reveals two distinct conformations of the flap lining the active-site cavity. Conclusions: The mode of binding of the inhibitor, and a comparison between the native and inhibited urease structures, indicate a novel mechanism for enzymatic urea hydrolysis which reconciles the available structural and biochemical data.
1999
Benini, S., Rypniewski, W.R., Wilson, K.S., Miletti, S., Ciurli, S., Mangani, S. (1999). A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacillus pasteurii: why urea hydrolysis casts two nickels. STRUCTURE, 7(2), 205-216 [10.1016/S0969-2126(99)80026-4].
File in questo prodotto:
File Dimensione Formato  
urease_Structure1999.pdf

non disponibili

Tipologia: Post-print
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 1.32 MB
Formato Adobe PDF
1.32 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/33014
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo