title: Genetic analysis of the minimal replicon of the Lactococcus lactis subsp. lactis biovar diacetylactis citrate plasmid.
abstract: Using a combination of mutagenesis with the transposon gamma delta and polymerase chain reaction subcloning, the essential elements of the replication region of the Lactococcus lactis subsp. lactis biovar diacetylactis citrate plasmid have been identified. An open reading frame, coding for a protein with homology to Rep proteins from other Lactococcus plasmids, is essential. This protein is trans-acting and could not be replaced by the Rep protein from another Lactococcus plasmid. A second open reading frame immediately downstream from the first could be removed or inactivated with no apparent effect on plasmid replication. A region containing two 10 bp direct repeats and three tandem repeats of a 22 bp sequence, immediately upstream of the essential open reading frame, is also essential and probably includes the origin of replication. A 181-bp DNA fragment containing this region was sufficient to allow replication in Lactococcus if the trans-acting protein was provided on another replicon. Single-stranded replication intermediates could not be detected, suggesting that the citrate plasmid uses theta replication rather than rolling-circle replication.
authors.affiliation: Institute of Life Sciences and Chemistry, Roskilde University Center, Denmark.
authors.forename: M L
authors.initials: ML
authors.lastname: Pedersen
authors.forename: K R
authors.initials: KR
authors.lastname: Arnved
authors.forename: E
authors.initials: E
authors.lastname: Johansen
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002951:Citrates / Q000378:metabolism*; D019343:Citric Acid; D003001:Cloning, Molecular; D004265:DNA Helicases; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004268:DNA-Binding Proteins; D005816:Genetic Complementation Test; D013294:Lactococcus lactis / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D012093:Replicon / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D019343:Citric Acid; D004265:DNA Helicases