title: Plasmids in the driving seat: The regulatory RNA Rcd gives plasmid ColE1 control over division and growth of its E. coli host.
abstract: Regulation by non-coding RNAs was found to be widespread among plasmids and other mobile elements of bacteria well before its ubiquity in the eukaryotic world was suspected. As an increasing number of examples was characterised, a common mechanism began to emerge. Non-coding RNAs, such as CopA and Sok from plasmid R1, or RNAI from ColE1, exerted regulation by refolding the secondary structures of their target RNAs or modifying their translation. One regulatory RNA that seemed to swim against the tide was Rcd, encoded within the multimer resolution site of ColE1. Required for high fidelity maintenance of the plasmid in recombination-proficient hosts, Rcd was found to have a protein target, elevating indole production by stimulating tryptophanase. Rcd production is up-regulated in dimer-containing cells and the consequent increase in indole is part of the response to the rapid accumulation of dimers by over-replication (known as the dimer catastrophe). It is proposed that indole simultaneously inhibits cell division and plasmid replication, stopping the catastrophe and allowing time for the resolution of dimers to monomers. The idea of a plasmid-mediated cell division checkpoint, proposed but then discarded in the 1980s, appears to be enjoying a revival.
authors.affiliation: Department of Genetics, Downing Site, University of Cambridge, Cambridge CB2 3EH, United Kingdom. Electronic address: h.gaimster@uea.ac.uk.
authors.forename: Hannah
authors.initials: H
authors.lastname: Gaimster
authors.affiliation: Department of Genetics, Downing Site, University of Cambridge, Cambridge CB2 3EH, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Summers
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D027682:Cation Transport Proteins / Q000235:genetics; D000073840:Copper-Transporting ATPases; D004261:DNA Replication; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007211:Indoles / Q000378:metabolism; D010957:Plasmids / Q000235:genetics*; D014368:Tryptophanase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D029968:Escherichia coli Proteins; D007211:Indoles; C042833:ROM protein, Bacteria; D000251:Adenosine Triphosphatases; D014368:Tryptophanase; D000073840:Copper-Transporting ATPases; C000612460:copA protein, E coli
keywords: Cell division checkpoint; Indole; Plasmid maintenance; Regulatory RNA; Signalling