Integrase-Mediated Recombination of the bel-1 Gene Cassette Encoding the Extended-Spectrum β-Lactamase BEL-1

Abstract

Integrons are genetic elements that can acquire and rearrange gene cassettes. The gene encodes an extended-spectrum β-lactamase, BEL-1, that is present at the second position of the variable region of class 1 integrons identified in The mobility of the gene cassette was analyzed under physiological conditions and with the integrase gene being overexpressed. Cassette mobility in was detected by excision/integration into the recipient integron In on the conjugative plasmid R388 with the overproduced integrase. Despite several antibiotic pressures, the cassette remained at the second position in the integron, highlighting its stability in Overexpression of the integrase gene in induced cassette recombination. However, cassettes containing two genes ( and or and ) were excised, suggesting that the cassette site was defective. We show that is a stable gene cassette under physiological growth conditions, irrespective of the selective antibiotic pressure, that may be mobilized upon overexpression of the integrase gene.

Genetic features of BEL-1-producing and KPC-2-producing E. coli from hospital wastewater: human source or sewages adaptation

“…The second notable feature is the type 3 integrase carrying bla BEL-1 that we found in our isolates, which is also present in the previous C. freundii and K. pneumoniae isolates. To date, the bla BEL-1 has usually been found in cassettes with class 1 integrons in P. aeruginosa (Bouheraoua et al 2018 ) , and had only been observed associated with the class 3 integrase in the previously reported K. pneumoniae isolate from Portugal (Papagiannitsis et al 2015 ). The class 3 integrase is not frequent in collections of multidrug-resistant isolates and has not been detected in isolates from healthy volunteers in Spain (Vinué et al 2008 ) or in a population-based study in France (Laroche et al 2009 ).…”