The majority of lactococcal plasmids carry a highly related replicon

Microbiology. 1994 Jun;140 ( Pt 6):1291-300. doi: 10.1099/00221287-140-6-1291.


DNA sequence analysis and Southern hybridizations, together with complementation experiments, were used to study relationships between lactococcal plasmid replicons. pWVO2, pWVO4 and pWVO5, which co-exist in Lactococcus lactis subsp. cremoris Wg2, and pIL7 (isolated from another strain) all contained a functional replication region which appeared to be very similar to that of some known lactococcal plasmids. They contain a gene encoding a highly conserved RepB protein (60-80% amino acid identity between pWVO2, pWVO4 and pWVO5), which is essential for replication. When supplied in trans, repB of pWVO2 complemented a repB deficiency of pWVO5. Upstream of the repB gene, all these plasmids contain a strongly conserved region including a 22 bp sequence tandemly repeated three-and-a-half times, and an A/T-rich region. The similarity with pWVO2, which is known to replicate via a theta mechanism, suggests that all plasmids of this family are capable of theta replication. Southern hybridizations revealed that many lactococcal strains contain plasmids of this family.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Base Sequence
  • Blotting, Southern
  • DNA Replication
  • DNA, Bacterial / genetics*
  • Genes, Bacterial
  • Genetic Complementation Test
  • Lactococcus lactis / genetics*
  • Molecular Sequence Data
  • Open Reading Frames / genetics
  • Plasmids / classification
  • Plasmids / genetics*
  • Replicon*
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid
  • Species Specificity


  • Bacterial Proteins
  • DNA, Bacterial
  • RepB protein, Bacteria

Associated data

  • GENBANK/L02920
  • GENBANK/L06274
  • GENBANK/X56550
  • GENBANK/Z25475
  • GENBANK/Z25476
  • GENBANK/Z25477