title: Characterization of replication and conjugation of Streptomyces circular plasmids pFP1 and pFP11 and their ability to propagate in linear mode with artificially attached telomeres.
abstract: Many Streptomyces species harbor circular plasmids (8 to 31 kb) as well as linear plasmids (12 to 1,700 kb). We report the characterization of two newly detected circular plasmids, pFP11 (35,139 bp) and pFP1 (39,360 bp). As on linear plasmids, their replication loci comprise repA genes and adjacent iterons, to which RepA proteins bind specifically in vitro. Plasmids containing the minimal iterons plus the repA locus of pFP11 were inherited extremely unstably; par and additional loci were required for stable inheritance. Surprisingly, plasmids containing replication loci from pFP11 or Streptomyces circular plasmid SCP2 but not from pFP1, SLP1, or pIJ101 propagated in a stable linear mode when the telomeres of a linear plasmid were attached. These results indicate bidirectional replication for pFP11 and SCP2. Both pFP11 and pFP1 contain, for plasmid transfer, a major functional traB gene (encoding a DNA translocase typical for Streptomyces plasmids) as well as, surprisingly, a putative traA gene (encoding a DNA nickase, characteristic of single-stranded DNA transfer of gram-negative plasmids), but this did not appear to be functional, at least in isolation.
authors.affiliation: Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, People's Republic of China.
authors.forename: Ran
authors.initials: R
authors.lastname: Zhang
authors.forename: Ana
authors.initials: A
authors.lastname: Zeng
authors.forename: Ping
authors.initials: P
authors.lastname: Fang
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Qin
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003227:Conjugation, Genetic; D004265:DNA Helicases / Q000235:genetics; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004270:DNA, Circular / Q000235:genetics / Q000378:metabolism; D023061:Gene Order; D008969:Molecular Sequence Data; D010957:Plasmids; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000235:genetics*; D016615:Telomere; D015534:Trans-Activators / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004270:DNA, Circular; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases