title: Identification and characterization of conjugative transposons CTn86 and CTn9343 in Bacteroides fragilis strains.
abstract: The related genetic elements flanking the Bacteroides fragilis pathogenicity island (PAI) in enterotoxigenic B. fragilis (ETBF) 86-5443-2-2 and also present in pattern III nontoxigenic B. fragilis (NTBF) NCTC 9343 were defined as putative conjugative transposons (CTns), designated CTn86 and CTn9343, respectively (A. A. Franco, J. Bacteriol. 181:6623-6633, 2004). CTn86 and CTn9343 have the same basic structures except that their encoded transposases have low similarity and CTn9343 lacks the B. fragilis PAI and contains an extra 7-kb region not present in CTn86. In this study, using DNA hybridization and PCR analysis, we characterized the genetic element flanking the PAI in a collection of ETBF strains and the related genetic elements in a collection of NTBF pattern III strains. We found that in all 123 ETBF strains, the PAI is contained in a genetic element similar to CTn86. Of 73 pattern III strains, 26 (36%) present a genetic element similar to CTn9343, 38 (52%) present a genetic element similar to CTn9343 but lack the 7-kb region that is also absent in CTn86 (CTn9343-like element), and 9 (12%) present a genetic element similar to CTn86 but lacking the PAI (CTn86-like element). In addition to containing CTn86, ETBF strains can also contain CTn9343, CTn9343-like, or CTn86-like elements. CTn86, CTn9343, CTn86-like, and CTn9343-like elements were found exclusively in B. fragilis strains and predominantly in division I, cepA-positive strains.
authors.affiliation: Division of Infectious Diseases, Johns Hopkins University School of Medicine, Cancer Research Building II, 1550 Orleans Street, Loading Dock, Room 1M04, Baltimore, MD 21205, USA.
authors.forename: Simy L
authors.initials: SL
authors.lastname: Buckwold
authors.forename: Nadja B
authors.initials: NB
authors.lastname: Shoemaker
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Sears
authors.forename: Augusto A
authors.initials: AA
authors.lastname: Franco
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D001441:Bacteroides fragilis / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D022761:Gene Transfer, Horizontal; D044404:Genomic Islands / Q000235:genetics; D006801:Humans; D008666:Metalloendopeptidases / Q000235:genetics; D009693:Nucleic Acid Hybridization / Q000379:methods; D016133:Polymerase Chain Reaction; D019895:Transposases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D019895:Transposases; C405031:Bacteroides fragilis toxin; D008666:Metalloendopeptidases