Molecular characterization of a carbapenem-hydrolyzing class A beta-lactamase, SFC-1, from Serratia fonticola UTAD54

Abstract

An environmental isolate of Serratia fonticola resistant to carbapenems contains a gene encoding a class A beta-lactamase with carbapenemase activity. The enzyme was designated SFC-1. The bla(SFC-I) gene is contained in the chromosome of S. fonticola UTAD54 and is absent from other S. fonticola strains.

FIG. 1.

Nucleotide and deduced amino acid sequences of the SFC-1 gene and its upstream and downstream regions. The putative −10 region and a potential RBS are in bold. The inverted repeat sequences that can act as a terminator of transcription are shaded. The putative signal peptide for protein secretion is underlined. Amino acids that correspond to conserved domains of class A β-lactamases are shown in bold.

FIG. 2.

Dendrogram obtained from the multiple sequence alignment of 15 class A β-lactamases. The percent identity between the amino acid sequence of each enzyme and that of SFC-1 is indicated in brackets.

FIG. 3.

Hybridizations to I-CeuI fragments generated from the genome of S. fonticola UTAD54 and separated by pulsed-field gel electrophoresis. Lane 1, hybridization with SFC-1 probe; lane 2, hybridization with probe for naturally occurring class A β-lactamases of S. fonticola; lane 3, hybridization using a probe for rRNA genes; lane 4, concatemers of phage lambda DNA.