title: ACT-6, a novel plasmid-encoded class C β-lactamase in a Klebsiella pneumoniae isolate from China.
abstract: The purpose of this study was to investigate the phenotypic and molecular characterization of a novel plasmid-mediated AmpC-type β-lactamase in Klebsiella pneumoniae E701 isolated from Anhui province in China. In comparison with the ACT-1, sequence analysis revealed that there were 43 point mutations in the coding gene, and 10 of which led to amino-acid substitution. Resistance could be transferred by conjugation or transformation with plasmid DNA into E. coli JM109, which was due to the production of a β-lactamase with an isoelectric point of 8.4 named ACT-6. Cloning, expression, purification and kinetics were carried out to study the characterization of the novel AmpC-type β-lactamase. The results of MIC determinations and substrate profiles showed there was no significant difference in the activities of the novel enzyme and ACT-1. Moreover, the class 1 integron and the whole open reading frame of the novel AmpC-type β-lactamase from K.pneumoniae E701 were detectable in the same size plasmid. This is the first report on the emergence of the novel ACT-6 type β-lactamases in K. pneumoniae.
authors.affiliation: Department of Infectious Diseases, the First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
authors.forename: Yu-lin
authors.initials: YL
authors.lastname: Zhu
authors.forename: Xiao-ni
authors.initials: XN
authors.lastname: Zhang
authors.forename: Fan
authors.initials: F
authors.lastname: Gao
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.forename: Li-fen
authors.initials: LF
authors.lastname: Hu
authors.forename: Tai
authors.initials: T
authors.lastname: Ma
authors.forename: Jun
authors.initials: J
authors.lastname: Yin
authors.forename: Ying
authors.initials: Y
authors.lastname: Ye
authors.forename: Jia-bin
authors.initials: JB
authors.lastname: Li
mesh_terms: D000368:Aged; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D002681:China; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D007526:Isoelectric Point; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids; D017354:Point Mutation; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C558843:ACT-6 beta-lactamases; C048795:AmpC beta-lactamases; D001618:beta-Lactamases