title: Chromobacterium spp. harbour Ambler class A β-lactamases showing high identity with KPC.
abstract: The origin of KPC is unknown. The aim of this study was to detect progenitors of KPC in silico and to functionally verify their β-lactam hydrolysis activity.
  
  
  
  The sequence of KPC-2 was used to mine the NCBI protein sequence database. The best non-KPC hits were analysed by amino acid (aa) alignment and phylogenetic tree construction. Genes encoding KPC-2 homologues were expressed in Escherichia coli. The carbapenemase activities of the recombinant strains were characterized by the CarbaNP test and UV spectrophotometry and MICs of selected β-lactams were determined.
  
  
  
  Genes encoding the closest KPC-2 homologues were identified on the chromosome of Chromobacterium piscinae strain ND17 (CRP-1, 76% aa identity), Chromobacterium sp. C-61 (CRS-1, 70% aa identity) and Chromobacterium haemolyticum DSM19808 (CRH-1, 69% aa identity). All three Chromobacterium β-lactamases were phylogenetically more related to KPC than to other Ambler class A β-lactamases. The 27 bp region preceding the start codon of blaCRP-1 displayed high nucleotide identity to the corresponding region upstream from blaKPC (74%). Heterologous expression of blaCRP-1 and to a lesser extent of blaCRH-1 in E. coli significantly increased the MICs of meropenem and most cephalosporins. The CarbaNP test was positive for both recombinant strains, but spectrophotometric analysis confirmed higher carbapenemase activity for CRP-1-producing clones.
  
  
  
  The recovery of three class A β-lactamases with up to 76% aa identity to KPC from distinct Chromobacterium species is highly indicative of the role played by this genus in the evolution of KPC.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Dereje Dadi
authors.initials: DD
authors.lastname: Gudeta
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Valeria
authors.initials: V
authors.lastname: Bortolaia
authors.affiliation: Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Jayol
authors.affiliation: Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Poirel
authors.affiliation: Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland HFR-Hôpital Cantonal, Fribourg, Switzerland.
authors.forename: Patrice
authors.initials: P
authors.lastname: Nordmann
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark Department of Biomedical Sciences, Ross University School of Veterinary Medicine, St Kitts, West Indies lg@sund.ku.dk.
authors.forename: Luca
authors.initials: L
authors.lastname: Guardabassi
mesh_terms: D002861:Chromobacterium / Q000201:enzymology* / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015870:Gene Expression; D006868:Hydrolysis; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D017385:Sequence Homology; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics*; D047090:beta-Lactams / Q000378:metabolism*
chemical_list: D047090:beta-Lactams; D001618:beta-Lactamases