TY - JOUR
T1 - Increased Antimicrobial Resistance in a Novel CMY-54 AmpC-Type Enzyme with a GluLeu217-218 Insertion in the Ω-Loop
AU - Pérez-Llarena, Francisco José
AU - Vázquez-Ucha, Juan Carlos
AU - Kerff, Frédéric
AU - Zamorano, Laura
AU - Miró, Elisenda
AU - Cabral, María Póvoa
AU - Fleites, Ana
AU - Lantero, Marta
AU - Martínez-Martínez, Luis
AU - Oliver, Antonio
AU - Galleni, Moreno
AU - Navarro, Ferrán
AU - Beceiro, Alejandro
AU - Bou, Germán
N1 - Publisher Copyright:
© Copyright 2018, Mary Ann Liebert, Inc.
PY - 2018/6
Y1 - 2018/6
N2 - During a Spanish surveillance study, a natural variant of a CMY-type β-lactamase related to CMY-2 with a GluLeu217-218 insertion in the Ω-loop (designated CMY-54) was found to increase the minimum inhibitory concentractions to β-lactams in a clinical strain of Escherichia coli. The aim of this study was to characterize CMY-54 by genetic, microbiological, and biochemical analysis. The blaCMY-54 gene is encoded by a plasmid of around 100 kb that hybridizes with K and FIB probes. The genetic context of blaCMY-54 and blaCMY-2 genes was found to be very similar. E. coli expressing CMY-54 under isogenic conditions showed a clear fourfold to eightfold increase in MICs to penicillins, cefotaxime, ceftazidime, and aztreonam compared with CMY-2. The catalytic efficiencies of pure CMY-2 and CMY-54 proteins correlated with their microbiological parameters. CMY-2 protein was more resistant to thermal denaturation than CMY-54, indicating that the Ω-loop of CMY-54 may be wider and more relaxed and probably enables better accommodation of these antimicrobials. Otherwise, the higher stabilization of CMY-2 may induce a slight reduction of the dynamics of this enzyme and primarily affect the hydrolysis of some of the bulkiest antibiotics. In summary, the GluLeu217-218 insertion observed in CMY-54 compared to CMY-2 produces a β-lactamase with a distinctive catalytic efficacy for β-lactam antimicrobials likely caused by an increased flexibility slightly affecting the active site shape, highlighting the relevance of single mutations on the hydrolytic spectrum in class C β-lactamases.
AB - During a Spanish surveillance study, a natural variant of a CMY-type β-lactamase related to CMY-2 with a GluLeu217-218 insertion in the Ω-loop (designated CMY-54) was found to increase the minimum inhibitory concentractions to β-lactams in a clinical strain of Escherichia coli. The aim of this study was to characterize CMY-54 by genetic, microbiological, and biochemical analysis. The blaCMY-54 gene is encoded by a plasmid of around 100 kb that hybridizes with K and FIB probes. The genetic context of blaCMY-54 and blaCMY-2 genes was found to be very similar. E. coli expressing CMY-54 under isogenic conditions showed a clear fourfold to eightfold increase in MICs to penicillins, cefotaxime, ceftazidime, and aztreonam compared with CMY-2. The catalytic efficiencies of pure CMY-2 and CMY-54 proteins correlated with their microbiological parameters. CMY-2 protein was more resistant to thermal denaturation than CMY-54, indicating that the Ω-loop of CMY-54 may be wider and more relaxed and probably enables better accommodation of these antimicrobials. Otherwise, the higher stabilization of CMY-2 may induce a slight reduction of the dynamics of this enzyme and primarily affect the hydrolysis of some of the bulkiest antibiotics. In summary, the GluLeu217-218 insertion observed in CMY-54 compared to CMY-2 produces a β-lactamase with a distinctive catalytic efficacy for β-lactam antimicrobials likely caused by an increased flexibility slightly affecting the active site shape, highlighting the relevance of single mutations on the hydrolytic spectrum in class C β-lactamases.
KW - antimicrobial
KW - Escherichia coli
KW - extended-spectrum
KW - mechanisms
KW - microbial drug resistance
UR - http://www.scopus.com/inward/record.url?scp=85048055168&partnerID=8YFLogxK
U2 - 10.1089/mdr.2017.0017
DO - 10.1089/mdr.2017.0017
M3 - Article
C2 - 28665771
AN - SCOPUS:85048055168
SN - 1076-6294
VL - 24
SP - 527
EP - 533
JO - Microbial Drug Resistance
JF - Microbial Drug Resistance
IS - 5
ER -