Control of replication of plasmid R1: the duplex between the antisense RNA, CopA, and its target, CopT, is processed specifically in vivo and in vitro by RNase III

EMBO J. 1990 Jul;9(7):2331-40.


The replication frequency of IncFII plasmids is regulated through the availability of a rate-limiting protein, RepA. The synthesis of this protein is controlled post-transcriptionally by a small antisense RNA, CopA, which binds to the leader region of the RepA mRNA (CopT). In this communication we report studies of the IncFII plasmid R1. We show that the duplex between CopA and CopT is cleaved specifically in vivo. The in vivo cleavage maps to the same position as that resulting from in vitro cleavage of a CopA/CopT duplex by purified RNase III. By introducing plasmids carrying translational repA-lacZ fusions into cells deficient in RNase III we show that the expression of repA is elevated when RNase III activity is severely decreased. Hence, cleavage by RNase III seems to be a key event in the copy number control system of plasmid R1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Base Sequence
  • DNA Helicases*
  • DNA Replication*
  • DNA-Binding Proteins*
  • Endoribonucleases / metabolism*
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins*
  • Genotype
  • Molecular Sequence Data
  • Nucleotide Mapping
  • Oligonucleotide Probes
  • Proteins*
  • R Factors*
  • RNA / genetics*
  • RNA Probes
  • RNA Processing, Post-Transcriptional
  • RNA, Antisense
  • RNA, Messenger / antagonists & inhibitors
  • RNA, Messenger / genetics*
  • Restriction Mapping
  • Ribonuclease III
  • Single-Strand Specific DNA and RNA Endonucleases
  • Trans-Activators*


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Oligonucleotide Probes
  • Proteins
  • RNA Probes
  • RNA, Antisense
  • RNA, Messenger
  • Trans-Activators
  • replication initiator protein
  • RNA
  • Endoribonucleases
  • Ribonuclease III
  • ribonuclease III, E coli
  • Single-Strand Specific DNA and RNA Endonucleases
  • DNA Helicases