title: Characterization of the IncW cryptic plasmid pXV2 from Xanthomonas campestris pv. vesicatoria.
abstract: The gram-negative plant pathogen Xanthomonas campestris pv. vesicatoria strain Xv2 harbors an indigenous, cryptic plasmid pXV2 of 14.6 kb. This plasmid can only be maintained in Xanthomonas and is incapable of self-transmission. However, incompatibility testing classified it in IncW, a group containing the smallest number of naturally occurring, broad-host-range, conjugative plasmids. A pXV2 derivative containing only a 5.5-kb PstI fragment is stably maintained. Deletion of a 3.0-kb region from the PstI fragment causes a loss of plasmid stability. Nucleotide sequencing of the 2. 1-kb region essential for autonomous replication revealed a repA gene and a downstream noncoding region containing four iterons, two 17- and two 19-nt direct repeats, and an AT-rich region lying between the two sets of iterons. The sequence of the deduced RepA and the iterons shows homology to the RepA (39% identity) and the iterons, respectively, of the IncW plasmid pSa. Maxicell expression of the repA gene produced a protein of 35 kDa, a size similar to that deduced from the nucleotide sequence. Trans-complementation test confirmed that the repA gene and the iterons are indeed the essential elements for pXV2 replication.
authors.affiliation: Department of Microbiology, China Medical College, Taichung, Taiwan.
authors.forename: L T
authors.initials: LT
authors.lastname: Wu
authors.forename: Y H
authors.initials: YH
authors.lastname: Tseng
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004265:DNA Helicases; D004261:DNA Replication; D004268:DNA-Binding Proteins; D004720:Endonucleases; D004926:Escherichia coli; D008836:Micrococcal Nuclease; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids / Q000737:chemistry / Q000235:genetics*; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D015183:Restriction Mapping; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D016959:Xanthomonas campestris / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D011506:Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; C074002:nuc protein, staphylococcus; C045264:replication initiator protein; D004720:Endonucleases; D008836:Micrococcal Nuclease; D004265:DNA Helicases