skip to main content


Title: A Distal Disulfide Bridge in OXA-1 β-Lactamase Stabilizes the Catalytic Center and Alters the Dynamics of the Specificity Determining Ω Loop

Widespread antibiotic resistance, particularly when mediated by broad-spectrum β-lactamases, has major implications for public health. Substitutions in the active site often allow broad-spectrum enzymes to accommodate diverse types of β-lactams. Substitutions observed outside the active site are thought to compensate for the loss of thermal stability. The OXA-1 clade of class D β-lactamases contains a pair of conserved cysteines located outside the active site that forms a disulfide bond in the periplasm. In this paper, the effect of the distal disulfide bond on the structure and dynamics of OXA-1 was investigated via 4 μs molecular dynamics simulations. The results reveal that the disulfide promotes the preorganized orientation of the catalytic residues and affects the conformation of the functionally important Ω loop. Furthermore, principal component analysis reveals differences in the global dynamics between the oxidized and reduced forms, especially in the motions involving the Ω loop. A dynamical network analysis indicates that, in the oxidized form, in addition to its role in ligand binding, the KTG family motif is a central hub of the global dynamics. Finally, as activity of OXA-1 has been measured only in the reduced form, we suggest that accurate assessment of its functional profile would require oxidativemore » conditions mimicking periplasm.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Carnegie Mellon Univ., Pittsburgh, PA (United States); Univ. at Buffalo, NY (United States)
  2. Grand Valley State Univ., Allendale, MI (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; P41GM103712-01
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 121; Journal Issue: 15; Journal ID: ISSN 1520-6106
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE; National Inst. of Health (NIH) (United States)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1424461