The crystal structure of ESBL TLA-1 in complex with clavulanic acid reveals a second acylation site

Biochem Biophys Res Commun. 2020 Feb 5;522(2):545-551. doi: 10.1016/j.bbrc.2019.11.138. Epub 2019 Nov 25.


β-lactamases are the main molecules responsible for giving bacterial resistance against β-lactam antibiotics. The study of β-lactamases has allowed the development of antibiotics capable of inhibiting these enzymes. In this context, extended spectrum β-lactamase (ESBL) TLA-1 has spread in Escherichia coli and Enterobacter cloacae clinical isolates during the last 30 years in Mexico. In this research, the 3D structures of ESBL TLA-1 and TLA-1 S70G mutant, both ligand-free and in complex with clavulanic acid were determined by X-ray crystallography. Four clavulanic acid molecules were found in the structure of TLA-1, two of those were intermediaries of the acylation process and were localized covalently bound to two different amino acid residues, Ser70 and Ser237. The coordinates of TLA-1 in complex with clavulanic acid shows the existence of a second acylation site, additional to Ser70, which might be extendable to several members of the subclass A β-lactamases family. This is the first time that two serines involved in binding clavulanic acid has been reported and described to an atomic level.

Keywords: Acylation site; Clavulanic acid; Extended-spectrum β-lactamases; TLA-1.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acylation
  • Clavulanic Acid / metabolism*
  • Crystallography, X-Ray
  • Ligands
  • Models, Molecular
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Mutation / genetics
  • Static Electricity
  • beta-Lactamases / chemistry*
  • beta-Lactamases / metabolism*


  • Ligands
  • Mutant Proteins
  • Clavulanic Acid
  • TLA-1 beta-lactamase
  • beta-Lactamases