Duan K, Liu C Q, Supple S, Dunn N W
Department of Biotechnology, University of New South Wales, Sydney, Australia.
FEMS Microbiol Lett. 1998 Jul 15;164(2):419-26. doi: 10.1111/j.1574-6968.1998.tb13118.x.
pND324 belongs to a family of closely related theta-type plasmids from Lactococcus lactis. An antisense RNA, termed countertranscript (ctRNA), was identified which is complementary to the leader sequence of the mRNA that encodes RepB, a protein essential for plasmid replication. When the synthesis of ctRNA was abolished by site-directed mutagenesis within its promoter region, the mutant replicon showed a 1.8-fold increase in copy number. Similar ctRNA promoter sequences are readily identifiable in 12 other published lactococcal theta-type plasmids, suggesting that they all encode a similar ctRNA-mediated regulatory mechanism.
