title: Three small, cryptic plasmids from Aeromonas salmonicida subsp. salmonicida A449.
abstract: The nucleotide sequences of three small (5.2-5.6 kb) plasmids from Aeromonas salmonicida subsp. salmonicida A449 are described. Two of the plasmids (pAsa1 and pAsa3) use a ColE2-type replication mechanism while the third (pAsa2) is a ColE1-type replicon. Insertions in the Rep protein and oriV region of the ColE2-type plasmids provide subtle differences that allow them to be maintained compatibly. All three plasmids carry genes for mobilization (mobABCD), but transfer genes are absent and are presumably provided in trans. Two of the plasmids, pAsa1 and pAsa3, carry toxin-antitoxin gene pairs, most probably to ensure plasmid stability. One open reading frame (ORF), orf1, is conserved in all three plasmids, while other ORFs are plasmid-specific. A survey of A. salmonicida strains indicates that pAsa1 and pAsa2 are present in all 12 strains investigated, while pAsa3 is present in 11 and a fourth plasmid, pAsal1, is present in 7.
authors.affiliation: National Research Council Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, Canada B3H 3Z1. jessica.boyd@nrc.ca
authors.forename: Jessica
authors.initials: J
authors.lastname: Boyd
authors.forename: Jason
authors.initials: J
authors.lastname: Williams
authors.forename: Bruce
authors.initials: B
authors.lastname: Curtis
authors.forename: Catherine
authors.initials: C
authors.lastname: Kozera
authors.forename: Rama
authors.initials: R
authors.lastname: Singh
authors.forename: Michael
authors.initials: M
authors.lastname: Reith
mesh_terms: D000333:Aeromonas / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001483:Base Sequence; D002874:Chromosome Mapping; D017124:Conserved Sequence; D017931:DNA Primers; D004261:DNA Replication / Q000235:genetics; D005393:Fish Diseases / Q000382:microbiology*; D005667:Furunculosis / Q000382:microbiology / Q000662:veterinary*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D012487:Salmonidae; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; C083180:Mob protein, Bacteria