Enzyme kinetics and biochemical analysis of ImiS, the metallo-β-lactamase from Aeromonas sobria 163a

Abstract

The metallo-beta-lactamase from Aeromonas sobria 163a, ImiS, was isolated in a two stage purification procedure using protein affinity columns. Enzyme kinetics show that ImiS hydrolyses the carbapenems but displays poor activity against other beta-lactams. ImiS possesses the narrowest spectrum of activity of the Group 3 enzymes that have been analysed. Sequencing of the 40 N-terminal amino acids show this region to be identical to that of the CphA metallo-beta-lactamase from Aeromonas hydrophila (Massidda, Rossolini & Satta, 1991). Light scattering analysis indicates that ImiS is functionally active as a monomer.

Genetic and Biochemical Characterization of an Acquired Subgroup B3 Metallo-β-Lactamase Gene, bla AIM-1 , and Its Unique Genetic Context in Pseudomonas aeruginosa from Australia

“…Cultures of E. coli carrying pAIM-1 were grown overnight at 37°C in 4 liters of LB broth. A periplasmic protein preparation (30 mM Tris [pH 8.0], as previously described [41]) was obtained, thereby discarding cytoplasmic proteins and, thus, 70% of E. coli proteins. This protein solution was treated with 30% and 60% ammonium sulfate solutions to precipitate the proteins, which were removed by centrifugation.…”

The Rapid Induction of Carbapenem-Resistance in an <i>Aeromonas dhakensis</i> Blood Isolate

“…Aeromonas species have chromosomal genes, such as cphA and imiS, encoding metallo-b-carbapenemase, which are not commonly expressed, but inducible. These genes have similar sequences and the enzymes can hydrolyze carbapenems efficiently (2,3). To understand the mechanism underlying the development of resistance to carbapenem, we analyzed the genetic homology between the blood isolates and the gene expression levels of the chromosomal metallo-blactamase.…”

Metalo-beta-lactamases

“…(39,75,76) . Contudo, desde o início da década de 1990, novos genes que codificam MßLs têm sido descritos em patógenos clinicamente importantes, como Pseudomonas spp., Acinetobacter spp.…”