Publications

roles of trai protein with activities of cleaving and rejoining the single-stranded dna in both initiation and termination of conjugal dna transfer.	the plasmid r100 encodes the trai protein, which is required for conjugal dna transfer. trai has the activity of site- and strand-specific nicking of the supercoiled plasmid dna. the molecular mechanism of this specific nicking, which is supposed to be the initiation reaction of dna transfer, is not understood.	1997	9544702
complete nucleotide sequences of 93-kb and 3.3-kb plasmids of an enterohemorrhagic escherichia coli o157:h7 derived from sakai outbreak.	enterohemorrhagic escherichia coli (ehec) o157:h7, derived from an outbreak in sakai city, japan in 1996, possesses two kinds of plasmids: a 93-kb plasmid termed po157, found in clinical ehec isolates world-wide and a 3.3-kb plasmid termed posak1, prevalent in ehec strains isolated in japan. complete nucleotide sequences of both plasmids have been determined, and the putative functions of the encoded proteins and the cis-acting dna sequences have been analyzed. po157 shares strikingly similar ge ...	1998	9628576
regulatory mechanisms in expression of the tray-i operon of sex factor plasmid r100: involvement of traj and tray gene products.	the plasmid r100 encodes tra genes essential for conjugal dna transfer in escherichia coli. genetic evidence suggests that the traj gene encodes a positive regulator for the tray-i operon, which includes almost all the tra genes located downstream of traj. the molecular mechanism of regulation by traj, however, is not yet understood. tray is the most proximal gene in the tray-i operon. tray promotes dna transfer by binding to a site, sbya, near the origin of transfer. tray is suggested to have a ...	1998	9734780
two amino acid residues of transposase contributing to differential transposability of is1 elements in escherichia coli.	escherichia coli w3110 contains four types of is1 elements in the chromosome. using an insertion element entrapping system, we collected 116 is1 plasmid insertion mutants, which resulted from a minimum of 26 independent is1 insertion events. all of them had insertions of is1 of the is1a (is1e and is1g) type. inspection of the transposase sequences of the four is1 types and the is1 of the resistance plasmid r100 showed that two amino acid residues, his-193 and leu-217 of transposase, might contri ...	1998	9748470
sequence, identification and effect on conjugation of the rmoa gene of plasmid r100-1.	the rmoa gene was recently identified from two partially overlapping sequences corresponding to a region close to the end of the tra operon of plasmid r100. its putative amino acid sequence showed strong homology to the hha protein of escherichia coli and ymoa protein of yersinia enterocolitica, which are modulators of gene expression in response to environmental stimuli. we have cloned the rmoa gene from plasmid r100-1 in puc19 and obtained the complete nucleotide sequence, which was previously ...	1998	9851035
the aada gene of plasmid r100 confers resistance to spectinomycin and streptomycin in myxococcus xanthus.	plasmids with the aada gene from plasmid r100, which confers resistance to the aminoglycosides spectinomycin and streptomycin in escherchia coli, can be introduced into wild-type myxococcus xanthus, strain dk1622, by electroporation. recombinant m. xanthus strains with integrated plasmids carrying the aada gene acquire resistance to high levels of these antibiotics. selection for aada in m. xanthus can be carried out independently of, or simultaneously with, selection for resistance to kanamycin ...	1998	9852026
transcription of the transfer genes tray and tram of the antibiotic resistance plasmid r100-1 is linked.	three separate tray deletion mutants of r100-1 were prepared by allele replacement. these mutants retained the ability to transfer at a level 100 times greater than r100 and 1/50 that of the parental r100-1. the mutants were complemented to normal r100-1 transfer levels by pdsp06, a multicopy tray clone. comparison of transcripts initiated at the tray promoter, p(y), by primer extension experiments showed that there was no detectable p(y) activity in r100 and that the level of p(y) activity in t ...	2000	10610818
locus of enterocyte effacement from citrobacter rodentium: sequence analysis and evidence for horizontal transfer among attaching and effacing pathogens.	the family of attaching and effacing (a/e) bacterial pathogens, which includes diarrheagenic enteropathogenic escherichia coli (epec) and enterohemorrhagic e. coli (ehec), remains a significant threat to human and animal health. these bacteria intimately attach to host intestinal cells, causing the effacement of brush border microvilli. the genes responsible for this phenotype are encoded in a pathogenicity island called the locus of enterocyte effacement (lee). citrobacter rodentium is the only ...	2001	11553577
interference of mrna function by sequence-specific endoribonuclease pemk.	in escherichia coli, programmed cell death is mediated through the system called "addiction module," which consists of a pair of genes encoding a stable toxin and a labile antitoxin. the pemi-pemk system is an addiction module present on plasmid r100. it helps to maintain the plasmid by post-segregational killing in e. coli population. here we demonstrate that purified pemk, the toxin encoded by the pemi-pemk addiction module, inhibits protein synthesis in an e. coli cell-free system, whereas th ...	2004	15024022
complete nucleotide sequence of a 92-kilobase plasmid harboring the ctx-m-15 extended-spectrum beta-lactamase involved in an outbreak in long-term-care facilities in toronto, canada.	a major outbreak involving an escherichia coli strain that was resistant to expanded-spectrum cephalosporins occurred in toronto and surrounding regions in 2000 to 2002. we report the complete sequence of a plasmid, pc15-1a, that was found associated with the outbreak strain. plasmid pc15-1a is a circular molecule of 92,353 bp consisting of two distinct regions. the first is a 64-kb region that is essentially homologous to the non-r-determinant region of plasmid r100 except for several point mut ...	2004	15388431
molecular characterization of a dna fragment carrying the basic replicon of ptuc100, the natural plasmid encoding the peptide antibiotic microcin j25 system.	the escherichia coli plasmid ptuc100 encodes production of, and immunity to, the peptide antibiotic microcin j25. in the present study, an approximately 8-kb fragment immediately adjacent to the previously sequenced microcin region was isolated and its dna sequence was determined. the main features of the newly characterized region are: (i) a basic replicon which is almost identical to that of the repfiia plasmid r100; (ii) two orfs with 96% identity to two orfs of unknown function on po157, a l ...	2004	15848229
regulation of conjugal transfer by lrp and dam methylation in plasmid r100.	conjugal transfer of the f-like plasmid r100 occurs at higher frequencies in the absence of dna adenine methylation. lower levels of r100-encoded finp rna were found in a dam host, suggesting that dam methylation regulates finp rna synthesis. lack of the leucine-responsive regulatory protein (lrp) causes a decrease in r100 plasmid transfer, indicating that lrp is an activator of r100-mediated conjugation. hence, host-encoded regulators previously described for the salmonella virulence plasmid (p ...	2005	16562380
sequence analysis of pkf3-70 in klebsiella pneumoniae: probable origin from r100-like plasmid of escherichia coli.	klebsiella pneumoniae is a clinically significant species of bacterium which causes a variety of diseases. clinical treatment of this bacterial infection is greatly hindered by the emergence of multidrug-resistant strains. the resistance is largely due to the acquisition of plasmids carrying drug-resistant as well as pathogenic genes, and its conjugal transfer facilitates the spread of resistant phenotypes.	2010	20066042
the transfer operon of plasmid r1 extends beyond fino into the downstream replication genes.	fino is the final gene in the 35.4 kb transfer operon of incfi plasmid f that is known to be involved in self-conjugative transfer. the genetic region distal to fino separates the conjugation and replication control modules of incfii plasmid r100 and carries uncharacterized genes not found in plasmid f. however, comparison of the r100 gene organization with database entries of f-like plasmids suggests its broad conservation. we determined the dna sequence of this region of incfii plasmid r1 and ...	2010	21145348