title: Genetic and biochemical characterization of FUS-1 (OXA-85), a narrow-spectrum class D beta-lactamase from Fusobacterium nucleatum subsp. polymorphum.
abstract: Previous studies have reported beta-lactamase-mediated penicillin resistance in Fusobacterium nucleatum, but no beta-lactamase gene has yet been identified in this species. An F. nucleatum subsp. polymorphum strain resistant to penicillin and amoxicillin was isolated from a human periodontitis sample. DNA cloning and sequencing revealed a 765-bp open reading frame encoding a new class D beta-lactamase named FUS-1 (OXA-85). A recombinant Escherichia coli strain carrying the bla(FUS-1) gene exhibited resistance to amoxicillin with a moderate decrease in the MICs with clavulanic acid. The bla(FUS-1) gene was found in two additional clonally unrelated F. nucleatum subsp. polymorphum isolates. It was located on the chromosome in a peculiar genetic environment where a gene encoding a putative transposase-like protein is found, suggesting a possible acquisition of this class D beta-lactamase gene. The FUS-1 enzyme showed the closest ancestral relationship with OXA-63 from Brachyspira pilosicoli (53% identity) and with putative chromosomal beta-lactamases of Campylobacter spp. (40 to 42% identity). FUS-1 presents all of the conserved structural motifs of class D beta-lactamases. Kinetic analysis revealed that FUS-1 exhibits a narrow substrate profile, efficiently hydrolyzing benzylpenicillin and oxacillin. FUS-1 was poorly inactivated by clavulanate and NaCl. FUS-1 is the first example of a class D beta-lactamase produced by a gram-negative, anaerobic, rod-shaped bacterium to be characterized.
authors.affiliation: Laboratoire de Bactériologie et Epidémiologie Moléculaire, Université de Nice, Centre Hospitalier Universitaire de Nice, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Voha
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Docquier
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Rossolini
authors.forename: Thierry
authors.initials: T
authors.lastname: Fosse
mesh_terms: D000595:Amino Acid Sequence; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D019818:Clavulanic Acid / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D016967:Fusobacterium nucleatum / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification; D005798:Genes, Bacterial; D006801:Humans; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D010406:Penicillins / Q000494:pharmacology; D010802:Phylogeny; D017433:Protein Structure, Secondary; D012492:Salts / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D012492:Salts; D019818:Clavulanic Acid; D000658:Amoxicillin; D001618:beta-Lactamases