AUTHOR=Cao Thinh-Phat , Yi Hyojeong , Dhanasingh Immanuel , Ghosh Suparna , Choi Jin Myung , Lee Kun Ho , Ryu Seol , Kim Heenam Stanley , Lee Sung Haeng TITLE=Non-catalytic-Region Mutations Conferring Transition of Class A β-Lactamases Into ESBLs JOURNAL=Frontiers in Molecular Biosciences VOLUME=7 YEAR=2020 URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2020.598998 DOI=10.3389/fmolb.2020.598998 ISSN=2296-889X ABSTRACT=

Despite class A ESBLs carrying substitutions outside catalytic regions, such as Cys69Tyr or Asn136Asp, have emerged as new clinical threats, the molecular mechanisms underlying their acquired antibiotics-hydrolytic activity remains unclear. We discovered that this non-catalytic-region (NCR) mutations induce significant dislocation of β3-β4 strands, conformational changes in critical residues associated with ligand binding to the lid domain, dynamic fluctuation of Ω-loop and β3-β4 elements. Such structural changes increase catalytic regions’ flexibility, enlarge active site, and thereby accommodate third-generation cephalosporin antibiotics, ceftazidime (CAZ). Notably, the electrostatic property around the oxyanion hole of Cys69Tyr ESBL is significantly changed, resulting in possible additional stabilization of the acyl-enzyme intermediate. Interestingly, the NCR mutations are as effective for antibiotic resistance by altering the structure and dynamics in regions mediating substrate recognition and binding as single amino-acid substitutions in the catalytic region of the canonical ESBLs. We believe that our findings are crucial in developing successful therapeutic strategies against diverse class A ESBLs, including the new NCR-ESBLs.