2uyx
From Proteopedia
| Line 4: | Line 4: | ||
==Overview== | ==Overview== | ||
| - | Metallo-beta-lactamases are zinc-dependent hydrolases that inactivate | + | Metallo-beta-lactamases are zinc-dependent hydrolases that inactivate beta-lactam antibiotics, rendering bacteria resistant to them. Asp-120 is fully conserved in all metallo-beta-lactamases and is central to catalysis. Several roles have been proposed for Asp-120, but so far there is no agreed consensus. We generated four site-specifically substituted variants of the enzyme BcII from Bacillus cereus as follows: D120N, D120E, D120Q, and D120S. Replacement of Asp-120 by other residues with very different metal ligating capabilities severely impairs the lactamase activity without abolishing metal binding to the mutated site. A kinetic study of these mutants indicates that Asp-120 is not the proton donor, nor does it play an essential role in nucleophilic activation. Spectroscopic and crystallographic analysis of D120S BcII, the least active mutant bearing the weakest metal ligand in the series, reveals that this enzyme is able to accommodate a dinuclear center and that perturbations in the active site are limited to the Zn2 site. It is proposed that the role of Asp-120 is to act as a strong Zn2 ligand, locating this ion optimally for substrate binding, stabilization of the development of a partial negative charge in the beta-lactam nitrogen, and protonation of this atom by a zinc-bound water molecule. |
==About this Structure== | ==About this Structure== | ||
| Line 15: | Line 15: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Bennett, B.]] | [[Category: Bennett, B.]] | ||
| - | [[Category: Fabiane, S | + | [[Category: Fabiane, S M.]] |
| - | [[Category: Kowalski, J | + | [[Category: Kowalski, J M.]] |
| - | [[Category: Larrull, L | + | [[Category: Larrull, L I.]] |
| - | [[Category: Sutton, B | + | [[Category: Sutton, B J.]] |
| - | [[Category: Vila, A | + | [[Category: Vila, A J.]] |
[[Category: GOL]] | [[Category: GOL]] | ||
[[Category: ZN]] | [[Category: ZN]] | ||
| Line 29: | Line 29: | ||
[[Category: zinc]] | [[Category: zinc]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:51:42 2008'' |
Revision as of 16:51, 21 February 2008
|
METALLO-BETA-LACTAMASE (1BC2) SINGLE POINT MUTANT D120S
Overview
Metallo-beta-lactamases are zinc-dependent hydrolases that inactivate beta-lactam antibiotics, rendering bacteria resistant to them. Asp-120 is fully conserved in all metallo-beta-lactamases and is central to catalysis. Several roles have been proposed for Asp-120, but so far there is no agreed consensus. We generated four site-specifically substituted variants of the enzyme BcII from Bacillus cereus as follows: D120N, D120E, D120Q, and D120S. Replacement of Asp-120 by other residues with very different metal ligating capabilities severely impairs the lactamase activity without abolishing metal binding to the mutated site. A kinetic study of these mutants indicates that Asp-120 is not the proton donor, nor does it play an essential role in nucleophilic activation. Spectroscopic and crystallographic analysis of D120S BcII, the least active mutant bearing the weakest metal ligand in the series, reveals that this enzyme is able to accommodate a dinuclear center and that perturbations in the active site are limited to the Zn2 site. It is proposed that the role of Asp-120 is to act as a strong Zn2 ligand, locating this ion optimally for substrate binding, stabilization of the development of a partial negative charge in the beta-lactam nitrogen, and protonation of this atom by a zinc-bound water molecule.
About this Structure
2UYX is a Single protein structure of sequence from Bacillus cereus with and as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Asp-120 locates Zn2 for optimal metallo-beta-lactamase activity., Llarrull LI, Fabiane SM, Kowalski JM, Bennett B, Sutton BJ, Vila AJ, J Biol Chem. 2007 Jun 22;282(25):18276-85. Epub 2007 Apr 10. PMID:17426028
Page seeded by OCA on Thu Feb 21 18:51:42 2008
