2NXA

Structure of Zn-dependent Metallo-Beta-Lactamase from Bacillus Cereus R121H, C221D Double Mutant

Summary for 2NXA

• Entry DOI: 10.2210/pdb2nxa/pdb
• Descriptor: Beta-lactamase II, ZINC ION (3 entities in total)
• Functional Keywords: bacillus cereus, r121h-c221d double mutant, hydrolase
• Biological source: Bacillus cereus
• Total number of polymer chains: 1
• Total formula weight: 24352.03

Authors

Medrano Martin, F.J.,Vila, A.J.,Gonzalez, J.M. (deposition date: 2006-11-17, release date: 2007-05-22, Last modification date: 2023-08-30)

Primary citation

Gonzalez, J.M.,Medrano Martin, F.J.,Costello, A.L.,Tierney, D.L.,Vila, A.J.
The Zn2 position in metallo-beta-lactamases is critical for activity: a study on chimeric metal sites on a conserved protein scaffold.
J.Mol.Biol., 373:1141-1156, 2007

PubMed Abstract: Metallo-beta-lactamases (MbetaLs) are bacterial Zn(II)-dependent hydrolases that confer broad-spectrum resistance to beta-lactam antibiotics. These enzymes can be subdivided into three subclasses (B1, B2 and B3) that differ in their metal binding sites and their characteristic tertiary structure. To date there are no clinically useful pan-MbetaL inhibitors available, mainly due to the unawareness of key catalytic features common to all MbetaL brands. Here we have designed, expressed and characterized two double mutants of BcII, a di-Zn(II) B1-MbetaL from Bacillus cereus, namely BcII-R121H/C221D (BcII-HD) and BcII-R121H/C221S (BcII-HS). These mutants display modified environments at the so-called Zn2 site or DCH site, reproducing the metal coordination environments of structurally related metallohydrolases. Through a combination of structural and functional studies, we found that BcII-HD is an impaired beta-lactamase even as a di-Zn(II) enzyme, whereas BcII-HS exhibits the ability to exist as mono or di-Zn(II) species in solution, with different catalytic performances. We show that these effects result from an altered position of Zn2, which is incapable of providing a productive interaction with the substrate beta-lactam ring. These results indicate that the position of Zn2 is essential for a productive substrate binding and hydrolysis.

PubMed: 17915249
DOI: 10.1016/j.jmb.2007.08.031

Experimental method

X-RAY DIFFRACTION (2.29 Å)