Isolation and expression of a novel molecular class D beta-lactamase, OXA-61, from Campylobacter jejuni

Abstract

A novel beta-lactamase gene, blaOXA-61, from Campylobacter jejuni GC015 was cloned and its nucleotide sequence determined. blaOXA-61 encodes a protein of 257 amino acids in which the active-site STFK tetrad and conserved class D beta-lactamase motifs YGN and KTG were identified. A conserved sequence upstream of blaOXA-61 is required for expression in Campylobacter.

FIG. 1.

Nucleotide sequence of the bla_OXA-61(pGU0401) gene. The deduced amino acid sequence of OXA-61 is aligned with the respective codons. The β-lactamase active-site STFK tetrad and the conserved motifs YGN and KTG are shown in underlined boldface type. A 16-amino-acid signal peptide was deduced (using the program SignalP V1.1. at the Center for Biological Sequence Analysis [http://www.cbs.dtu.dk/services/SignalP/] [13]) and is indicated in italics; the deduced cleavage site is indicated by a slash. The 122-bp conserved region directly upstream of the oxa-61 initiation codon is shaded. Putative C. jejuni promoter sequences (−10, −35) and the putative ribosome-binding site (RBS) (18) are underlined. The bracketed broken line indicates the nucleotide sequence deleted in recombinant plasmid pGU0403.