DOCQUIER JD, MUGNAIOLI C, PERILLI M, AMICOSANTE G, ROSSOLINI GM; Interscience Conference on Antimicrobial Agents and Chemotherapy (43rd: 2003: Chicago, Ill.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2003 Sep 14-17; 43: abstract no. C1-660.
University of Siena, Siena, Italy.
BACKGROUND: IMP-1 was the first acquired metallo-b -lactamase to be detected in clinical isolates of Pseudomonas spp. and Enterobacteriaceae. Subsequently, several variants of IMP-type enzymes have been identified, divergent by 1 to 15% aminoacid residues from IMP-1 and showing in some cases different kinetic properties. Here we report the characterization of a new IMP variant, IMP-13, that was found in a beta-lactam-resistant clinical isolate of Pseudomonas aeruginosa (isolate AT-07/02) from an Italian hospital. METHODS: Characterization of the bla[IMP-13] genetic support was carried out by PCR mapping and sequencing. The bla[IMP-13] gene was subcloned in the pET-9a expression vector and overexpressed in in Escherichia coli BL21(DE3). The IMP-13 protein was purified by conventional chromatography. Kinetic properties were determined with several beta-lactam substrates measuring hydrolysis rates under initial rate conditions. RESULTS: IMP-13 is a new variant that differs from IMP-1 by 15% amino acid residues at the level of the mature protein, being one of the most divergent variant so far identified. It is more similar to IMP-2 and IMP-8 (92 and 93%, respectively) and, unlike other IMP variants, it exhibits an acidic isoelectric pH. In AT-07/02, the new bla[IMP] determinant was found to be carried on a gene cassette inserted in a class 1 integron located on the chromosome, also containing an aacA4 aminoglycoside acetyltransferase determinant. The IMP-13 enzyme was overproduced in E. coli and purified (>95%). IMP-13 exhibits a broad substrate specificity. Comparative analysis of kinetic parameters revealed differences with IMP-1 with some substrates. CONCLUSIONS: IMP-13 is a new highly divergent IMP variant detected in P. aeruginosa. Results underscore the remarkable structural and functional heterogeneity that exists in this group of clinically relevant enzymes. Supported by EU-HP grant no. HPRN-CT-2002-00264
Publication Types:
Keywords:
- Escherichia coli
- IMP-8 enzyme
- Integrons
- Italy
- Pseudomonas aeruginosa
- beta-Lactamases
- beta-Lactams
Other ID:
UI: 102264737
From Meeting Abstracts