Analysis of the binding forces driving the tight interactions between beta-lactamase inhibitory protein-II (BLIP-II) and class A beta-lactamases

J Biol Chem. 2011 Sep 16;286(37):32723-35. doi: 10.1074/jbc.M111.265058. Epub 2011 Jul 20.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus anthracis / chemistry*
  • Bacillus anthracis / genetics
  • Bacillus anthracis / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Crystallography, X-Ray
  • Kinetics
  • Protein Structure, Quaternary
  • Streptomyces / chemistry*
  • Streptomyces / genetics
  • Streptomyces / metabolism
  • beta-Lactamase Inhibitors*
  • beta-Lactamases / chemistry*
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • beta-Lactamase Inhibitors
  • beta-lactamase-inhibitor protein, Streptomyces
  • beta-Lactamases