title: Diversity of naturally occurring Ambler class B metallo-β-lactamases in Erythrobacter spp.
abstract: OBJECTIVE
  In silico analysis identified a metallo-β-lactamase (MBL) in Erythrobacter litoralis HTCC2594, sharing 55% amino acid identity with NDM-1. The aim of this work was to characterize the chromosomally encoded MBLs from several Erythrobacter spp. that may represent potential reservoirs of acquired MBLs.
  
  
  METHODS
  Erythrobacter citreus, Erythrobacter flavus, Erythrobacter longus, Erythrobacter aquimaris and Erythrobacter vulgaris were from the Pasteur Institute collection, France. DNA was extracted and used for shotgun cloning, and β-lactamases were expressed in Escherichia coli. MICs for resulting E. coli recombinant strains were determined by Etest. The deduced amino acid sequences were analysed and compared with BLASTP. Enzymatic activity of bacterial extracts from recombinant E. coli strains was determined by UV spectrophotometry with imipenem (100 μM) as substrate.
  
  
  RESULTS
  Resulting E. coli recombinant strains harboured hypothetical MBL-encoding genes. MICs of β-lactams showed decreased susceptibility to carbapenems only for E. coli (pFLA-1) and E. coli (pLON-1), expressing the MBL from E. flavus and E. longus, respectively. MBLs from different Erythrobacter spp. shared weak amino acid identity, ranging from 45% to75% identity. They differed greatly from that of E. litoralis HTCC2594 (and NDM-1), sharing only 11%-23% identity. Enzymatic activity against imipenem was detectable but weak in all these recombinant E. coli strains, except E. coli (pFLA-1), in which specific activity was significantly higher.
  
  
  CONCLUSIONS
  Several chromosomally located MBLs have been identified from Erythrobacter spp. They share weak amino acid identity and are very weakly related to other acquired MBLs (10%-23%).
authors: Service de Bactériologie-Virologie, INSERM U914 'Emerging Resistance to Antibiotics',  Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine et Université Paris Sud, 94275 Le K.-Bicêtre,  France.
authors: Delphine
authors: D
authors: Girlich
authors: Laurent
authors: L
authors: Poirel
authors: Patrice
authors: P
authors: Nordmann
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D005602:France; D015378:Imipenem / Q000378:metabolism / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet; D042301:Sphingomonadaceae / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*; D047090:beta-Lactams / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D047090:beta-Lactams; D015378:Imipenem; D001618:beta-Lactamases