title: pSLA2-M of Streptomyces rochei is a composite linear plasmid characterized by self-defense genes and homology with pSLA2-L.
abstract: The 113,463-bp nucleotide sequence of the linear plasmid pSLA2-M of Streptomyces rochei 7434AN4 was determined. pSLA2-M had a 69.7% overall GC content, 352-bp terminal inverted repeats with 91% (321/352) identity at both ends, and 121 open reading frames. The rightmost 14.6-kb sequence was almost (14,550/14,555) identical to that of the coexisting 211-kb linear plasmid pSLA2-L. Adjacent to this homologous region an 11.8-kb CRISPR cluster was identified, which is known to function against phage infection in prokaryotes. This cluster region as well as another one containing two large membrane protein genes (orf78 and orf79) were flanked by direct repeats of 194 and 566 bp respectively. Hence the insertion of circular DNAs containing each cluster by homologous recombination was suggested. In addition, the orf71 encoded a Ku70/Ku80-like protein, known to function in the repair of double-strand DNA breaks in eukaryotes, but disruption of it did not affect the radiation sensitivity of the mutant. A pair of replication initiation genes (orf1-orf2) were identified at the extreme left end. Thus, pSLA2-M proved to be a composite linear plasmid characterized by self-defense genes and homology with pSLA2-L that might have been generated by multiple recombination events.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Yang
authors.forename: Toru
authors.initials: T
authors.lastname: Kurokawa
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Takahama
authors.forename: Yosi
authors.initials: Y
authors.lastname: Nindita
authors.forename: Susumu
authors.initials: S
authors.lastname: Mochizuki
authors.forename: Kenji
authors.initials: K
authors.lastname: Arakawa
authors.forename: Satoru
authors.initials: S
authors.lastname: Endo
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Kinashi
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001435:Bacteriophages / Q000737:chemistry / Q000235:genetics; D001482:Base Composition; D001483:Base Sequence; D017124:Conserved Sequence; D053903:DNA Breaks, Double-Stranded; D004261:DNA Replication; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry*; D055029:Inverted Repeat Sequences; D056265:Microbial Interactions; D008969:Molecular Sequence Data; D010957:Plasmids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D018741:Replication Origin; D015183:Restriction Mapping / Q000379:methods; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism / Q000821:virology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial