Regulation of replication of plasmid pBR322 in amino acid-starved Escherichia coli strains.
The stringent response causes inhibition of replication of plasmid pBR322 in amino acid-starved Escherichia coli cells whereas in relaxed mutants the replication of this plasmid proceeds for several hours. On the basis of density shift experiments and pulse-labelling experiments we showed that most of the pBR322 molecules begin replication during the relaxed response and the rate of plasmid DNA synthesis in unstarved and isoleucine-starved relA- bacteria is similar. We found that the Rom function plays a key role in the stringent control of plasmid pBR322 replication, as insertional inactivation of the rom gene causes amplification of pBR322rom- in both relA- and relA+ strains during amino acid starvation. Moreover, pUC19, which is a pBR322-derived plasmid lacking the rom gene, behaves like pBR322rom-, whereas introduction of the rom gene into the pUC19 replicon drives it into the pBR322 mode of replication in amino acid-starved bacteria. A model for the regulation of pBR322 plasmid DNA replication by Rom protein in amino acid-starved Escherichia coli strains is proposed.
Herman
A
A
Department of Molecular Biology, University of Gdańsk, Poland.
Wegrzyn
A
A
Wegrzyn
G
G
D000222:Adaptation, Physiological; D001120:Arginine / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002499:Centrifugation, Density Gradient; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D007532:Isoleucine / Q000378:metabolism; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C042833:ROM protein, Bacteria; D007532:Isoleucine; D001120:Arginine