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EBR-1, a novel Ambler subclass B1 beta-lactamase from Empedobacter brevis
Samuel Bellais1, Delphine Girlich, Amal Karim
1Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre Cédex, France.
Antimicrobial Agents and Chemotherapy
|September 18, 2002
Summary
Empedobacter brevis produces a novel class B beta-lactamase, EBR-1, conferring resistance to carbapenems and cephalosporins. This metalloenzyme shows potential for widespread clinical resistance in gram-negative infections.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Empedobacter brevis is a gram-negative aerobe implicated in hospital-acquired infections.
- This bacterium exhibits reduced susceptibility to expanded-spectrum cephalosporins and carbapenems.
Purpose of the Study:
- To clone and characterize the Ambler class B beta-lactamase gene bla(EBR-1) from E. brevis.
- To understand the enzymatic activity and classification of the novel beta-lactamase EBR-1.
Main Methods:
- Cloning and expression of the bla(EBR-1) gene in Escherichia coli.
- Purification and kinetic analysis of the beta-lactamase EBR-1.
- Determination of isoelectric point (pI) and molecular mass.
- Amino acid sequence comparison with known beta-lactamases.
Main Results:
- The bla(EBR-1) gene was successfully cloned and expressed.
- Purified beta-lactamase EBR-1 efficiently hydrolyzed penicillins, cephalosporins, and carbapenems, but not aztreonam.
- EBR-1 exhibited kinetic parameters similar to other class B enzymes, with a pI of 8.0 and molecular mass of approximately 25 kDa.
- EBR-1 was classified in functional subgroup 3a and molecular subclass B1, sharing significant amino acid identity with related metalloenzymes.
Conclusions:
- Beta-lactamase EBR-1 contributes to the reduced susceptibility of E. brevis to key antibiotics.
- EBR-1 represents a significant finding in the study of antibiotic resistance mechanisms in gram-negative bacteria.
- The characterization of EBR-1 provides insights into the evolution and spread of class B beta-lactamases.