title: High rate of mobilization for blaCTX-Ms.
abstract: We constructed a phylogenetic analysis of class A beta-lactamases and found that the blaCTX-Ms have been mobilized to plasmids approximately 10 times more frequently than other class A beta-lactamases. We also found that the blaCTX-Ms are descended from a common ancestor that was incorporated in ancient times into the chromosome of the ancestor of Kluyvera species through horizontal transfer. Considerable sequence divergence has occurred among the descendents of that ancestral gene sequence since that gene was inserted. That divergence has mainly occurred in the presence of purifying selection, which indicates a slow rate of evolution for blaCTX-Ms in the pre-antimicrobial drug era.
authors.affiliation: University of California, Merced, California 95344, USA. mbarlow@ucmerced.edu
authors.forename: Miriam
authors.initials: M
authors.lastname: Barlow
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Reik
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Jacobs
authors.forename: Mónica
authors.initials: M
authors.lastname: Medina
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Meyer
authors.forename: John E
authors.initials: JE
authors.lastname: McGowan
authors.forename: Fred C
authors.initials: FC
authors.lastname: Tenover
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D001618:beta-Lactamases / Q000145:classification* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D001618:beta-Lactamases