R391: a conjugative integrating mosaic comprised of phage, plasmid, and transposon elements.
The conjugative, chromosomally integrating element R391 is the archetype of the IncJ class of mobile genetic elements. Originally found in a South African Providencia rettgeri strain, R391 carries antibiotic and mercury resistance traits, as well as genes involved in mutagenic DNA repair. While initially described as a plasmid, R391 has subsequently been shown to be integrated into the bacterial chromosome, employing a phage-like integration mechanism closely related to that of the SXT element from Vibrio cholerae O139. Analysis of the complete 89-kb nucleotide sequence of R391 has revealed a mosaic structure consisting of elements originating in bacteriophages and plasmids and of transposable elements. A total of 96 open reading frames were identified; of these, 30 could not be assigned a function. Sequence similarity suggests a relationship of large sections of R391 to sequences from Salmonella, in particular those corresponding to the putative conjugative transfer proteins, which are related to the IncHI1 plasmid R27. A composite transposon carrying the kanamycin resistance gene and a novel insertion element were identified. Challenging the previous assumption that IncJ elements are plasmids, no plasmid replicon was identified on R391, suggesting that they cannot replicate autonomously.
Böltner
Dietmar
D
Department of Biological Sciences, University of Essex, Colchester, United Kingdom.
MacMahon
Claire
C
Pembroke
J Tony
JT
Strike
Peter
P
Osborn
A Mark
AM
D001435:Bacteriophages / Q000737:chemistry / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009030:Mosaicism; D016366:Open Reading Frames / Q000235:genetics / Q000502:physiology; D010802:Phylogeny; D010957:Plasmids; D011815:R Factors / Q000737:chemistry / Q000235:genetics*; D017422:Sequence Analysis, DNA; D016662:Virus Integration
D004251:DNA Transposable Elements; D004269:DNA, Bacterial