title: Characterization of the Porphyromonas gingivalis conjugative transposon CTnPg1: determination of the integration site and the genes essential for conjugal transfer.
abstract: In our previous study, extensive genomic rearrangements were found in two strains of the Gram-negative anaerobic bacterium Porphyromonas (Por.) gingivalis, and most of these rearrangements were associated with mobile genetic elements such as insertion sequences and conjugative transposons (CTns). CTnPg1, identified in Por. gingivalis strain ATCC 33277, was the first complete CTn reported for the genus Porphyromonas. In the present study, we found that CTnPg1 can be transferred from strain ATCC 33277 to another Por. gingivalis strain, W83, at a frequency of 10(-7) to 10(-6). The excision of CTnPg1 from the chromosome in a donor cell depends on an integrase (Int; PGN_0094) encoded in CTnPg1, whereas CTnPg1 excision is independent of PGN_0084 (a DNA topoisomerase I homologue; Exc) encoded within CTnPg1 and recA (PGN_1057) on the donor chromosome. Intriguingly, however, the transfer of CTnPg1 between Por. gingivalis strains requires RecA function in the recipient. Sequencing analysis of CTnPg1-integrated sites on the chromosomes of transconjugants revealed that the consensus attachment (att) sequence is a 13 bp sequence, TTTTCNNNNAAAA. We further report that CTnPg1 is able to transfer to two other bacterial species, Bacteroides thetaiotaomicron and Prevotella oralis. In addition, CTnPg1-like CTns are located in the genomes of other oral anaerobic bacteria, Porphyromonas endodontalis, Prevotella buccae and Prevotella intermedia, with the same consensus att sequence. These results suggest that CTns in the CTnPg1 family are widely distributed among oral anaerobic Gram-negative bacteria found in humans and play important roles in horizontal gene transfer among these bacteria.
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-7-1, Nagasaki 852-8588, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Naito
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-7-1, Nagasaki 852-8588, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Sato
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-7-1, Nagasaki 852-8588, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Shoji
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-7-1, Nagasaki 852-8588, Japan.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Yukitake
authors.affiliation: Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, Kihara 5200, Kiyotake, Miyazaki 889-1692, Japan.
authors.forename: Yoshitoshi
authors.initials: Y
authors.lastname: Ogura
authors.affiliation: Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, Kihara 5200, Kiyotake, Miyazaki 889-1692, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Global COE Program at Nagasaki University, Nagasaki 852-8588, Japan.|Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-7-1, Nagasaki 852-8588, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D001287:Attachment Sites, Microbiological / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D003227:Conjugation, Genetic; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D010510:Periodontal Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000235:genetics*; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D019426:Integrases; D011938:Rec A Recombinases; D004264:DNA Topoisomerases, Type I