Related Experiment Video
Updated: Jul 11, 2026

The Use of a β-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions
Published on: February 1, 2018
The Zn2 position in metallo-beta-lactamases is critical for activity: a study on chimeric metal sites on a conserved
Javier M González1, Francisco J Medrano Martín, Alison L Costello
1Departamento de Química Biológica, Instituto de Biología Molecular y Celular de Rosario, IBR-CONICET. Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, S2002LRK, Argentina.
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.
More Related Videos
Related Concept Videos
Ligand Binding and Linkage
Ligand Binding Sites
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...
Conserved Binding Sites
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Complexation Equilibria: Factors Influencing Stability of Complexes

