title: Analysis of the binding forces driving the tight interactions between beta-lactamase inhibitory protein-II (BLIP-II) and class A beta-lactamases.
abstract: β-Lactamases hydrolyze β-lactam antibiotics to provide drug resistance to bacteria. β-Lactamase inhibitory protein-II (BLIP-II) is a potent proteinaceous inhibitor that exhibits low picomolar affinity for class A β-lactamases. This study examines the driving forces for binding between BLIP-II and β-lactamases using a combination of presteady state kinetics, isothermal titration calorimetry, and x-ray crystallography. The measured dissociation rate constants for BLIP-II and various β-lactamases ranged from 10(-4) to 10(-7) s(-1) and are comparable with those found in some of the tightest known protein-protein interactions. The crystal structures of BLIP-II alone and in complex with Bacillus anthracis Bla1 β-lactamase revealed no significant side-chain movement in BLIP-II in the complex versus the monomer. The structural rigidity of BLIP-II minimizes the loss of the entropy upon complex formation and, as indicated by thermodynamics experiments, may be a key determinant of the observed potent inhibition of β-lactamases.
authors.affiliation: Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Brown
authors.forename: Dar-Chone
authors.initials: DC
authors.lastname: Chow
authors.forename: Banumathi
authors.initials: B
authors.lastname: Sankaran
authors.forename: Peter
authors.initials: P
authors.lastname: Zwart
authors.forename: B V Venkataram
authors.initials: BV
authors.lastname: Prasad
authors.forename: Timothy
authors.initials: T
authors.lastname: Palzkill
mesh_terms: D001408:Bacillus anthracis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D007700:Kinetics; D020836:Protein Structure, Quaternary; D013302:Streptomyces / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D065093:beta-Lactamase Inhibitors; C065596:beta-lactamase-inhibitor protein, Streptomyces; D001618:beta-Lactamases