title: Communication between the active site and the allosteric site in class A beta-lactamases.
abstract: Bacterial production of beta-lactamases, which hydrolyze beta-lactam type antibiotics, is a common antibiotic resistance mechanism. Antibiotic resistance is a high priority intervention area and one strategy to overcome resistance is to administer antibiotics with beta-lactamase inhibitors in the treatment of infectious diseases. Unfortunately, beta-lactamases are evolving at a rapid pace with new inhibitor resistant mutants emerging every day, driving the design and development of novel beta-lactamase inhibitors. Here, we examined the inhibitor recognition mechanism of two common beta-lactamases using molecular dynamics simulations. Binding of beta-lactamase inhibitor protein (BLIP) caused changes in the flexibility of regions away from the binding site. One of these regions was the H10 helix, which was previously identified to form a lid over an allosteric inhibitor binding site. Closer examination of the H10 helix using sequence and structure comparisons with other beta-lactamases revealed the presence of a highly conserved Trp229 residue, which forms a stacking interaction with two conserved proline residues. Molecular dynamics simulations on the Trp229Ala mutants of TEM-1 and SHV-1 resulted in decreased stability in the apo form, possibly due to loss of the stacking interaction as a result of the mutation. The mutant TEM-1 beta-lactamase had higher H10 fluctuations in the presence of BLIP, higher affinity to BLIP and higher cross-correlations with BLIP. Our results suggest that the H10 helix and specifically W229 are important modulators of the allosteric communication between the active site and the allosteric site.
authors: Chemical Engineering Department, Bogazici University, Bebek, 34342 Istanbul, Turkey.
authors: Deniz
authors: D
authors: Meneksedag
authors: Asligul
authors: A
authors: Dogan
authors: Pinar
authors: P
authors: Kanlikilicer
authors: Elif
authors: E
authors: Ozkirimli
mesh_terms: D000495:Allosteric Site; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D001618:beta-Lactamases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C065596:beta-lactamase-inhibitor protein, Streptomyces; C054882:beta-lactamase PIT-2; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1