title: Molecular characterisation of a 5.75-kb cryptic plasmid from Bifidobacterium breve NCFB 2258 and determination of mode of replication.
abstract: A small cryptic plasmid originating from Bifidobacterium breve NCFB 2258 was cloned and its complete nucleotide sequence determined. pCIBb1 is a circular DNA molecule, 5750 bp in size with a GC composition of 57%. Computer-assisted analysis identified 10 possible open reading frames (ORFs), seven of which could be assigned no function from homology searches. One ORF, rep (380 amino acids), was postulated to encode a replication protein similar to known replication proteins of rolling circle replicons, particularly those of the pC194 family. Demonstration of single-stranded forms of the plasmid in cell lysates that could be specifically degraded by S1 nuclease provided experimental evidence to substantiate a replication mechanism via single-stranded intermediates. Two other ORFs, par (199 amino acids) and an ftsK-like gene (286 amino acids), were assigned putative functions based on the presence of conserved motifs in their deduced proteins.
authors.affiliation: Department of Microbiology, University College, Cork, Ireland.
authors.forename: K
authors.initials: K
authors.lastname: O'Riordan
authors.forename: G F
authors.initials: GF
authors.lastname: Fitzgerald
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001644:Bifidobacterium / Q000235:genetics*; D003001:Cloning, Molecular; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids / Q000502:physiology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D015719:Single-Strand Specific DNA and RNA Endonucleases