title: The tap-tpg gene pair on the linear plasmid functions to maintain a linear topology of the chromosome in Streptomyces rochei.
abstract: Streptomyces rochei 7434AN4 carries three linear plasmids, pSLA2-L (211 kb), pSLA2-M (113 kb) and pSLA2-S (18 kb), their complete nucleotide sequences having been determined. Restriction and sequencing analysis revealed that the telomere sequences at both ends of the linear chromosome are identical to each other, are 98.5% identical to the right end sequences of pSLA2-L and pSLA2-M up to 3.1 kb from the ends and have homology to those of typical Streptomyces species. Mutant 2-39, which lost all the three linear plasmids, was found to carry a circularized chromosome. Sequence comparison of the fusion junction and both deletion ends revealed that chromosomal circularization occurred by terminal deletions followed by nonhomologous recombination. Curing of pSLA2-L from strain 51252, which carries only pSLA2-L, also resulted in terminal deletions in newly obtained mutants. The tap-tpg gene pair, which encodes a telomere-associated protein and a terminal protein for end patching, is located on pSLA2-L and pSLA2-M but has not hitherto been found on the chromosome. These results led us to the idea that the tap-tpg of pSLA2-L or pSLA2-M functions to maintain a linear chromosome in strain 7434AN4. This hypothesis was finally confirmed by complementation and curing experiments of the tap-tpg of pSLA2-M.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8530, Japan.
authors.forename: Yosi
authors.initials: Y
authors.lastname: Nindita
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: Cao
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Yang
authors.forename: Kenji
authors.initials: K
authors.lastname: Arakawa
authors.forename: Yuh
authors.initials: Y
authors.lastname: Shiwa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Michihira
authors.initials: M
authors.lastname: Tagami
authors.forename: Alexander
authors.initials: A
authors.lastname: Lezhava
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Kinashi
mesh_terms: D000595:Amino Acid Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics* / Q000648:ultrastructure*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D011995:Recombination, Genetic; D015183:Restriction Mapping; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000235:genetics*; D016615:Telomere / Q000235:genetics
chemical_list: D004269:DNA, Bacterial