An Origin of DNA Replication fromLactococcus lactis Bacteriophage c2

An origin of DNA relication was identified in the intergenic region between the early and late gene regions of prolate lactococcal phage c2. A DNA fragment containing this origin, designated ori, was shown to direct DNA replication in Lactococcus lactis but not in Escherichia coli. A comparison of ori with the corresponding regions of other prolate phages revealed strict conservation of the nucleotide sequence in one half of this intergenic region. This conserved region alone would not support DNA replication. No open reading frames were identified in theorifragment, suggesting that host factors alone are sufficient to initiate DNA replication atori.AnovelclassoflactococcalvectorsandE.coli-L.lactisshuttlevectorsbasedonorihavebeenconstructed.