Plasmid Evolution and Interaction between the Plasmid Addiction Stability Systems of Two Related Broad-Host-Range IncQ-Like Plasmids
Date
2004
Authors
Deane S.M.
Rawlings D.E.
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Abstract
Plasmid pTC-F14 contains a plasmid stability system called pas (plasmid addiction system), which consists of two proteins, a PasA antitoxin and a PasB toxin. This system is closely related to the pas of plasmid pTF-FC2 (81 and 72% amino acid identity for PasA and PasB, respectively) except that the pas of pTF-FC2 contains a third protein, PasC. As both pTC-F14 and pTF-FC2 are highly promiscuous broad-host-range plasmids isolated from bacteria that share a similar ecological niche, the plasmids are likely to encounter each other. We investigated the relative efficiencies of the two stability systems and whether they had evolved apart sufficiently for each pas to stabilize a plasmid in the presence of the other. The three-component pTF-FC2 pas was more efficient at stabilization of a heterologous tester plasmid than the two component pas of pTC-F14 in Escherichia coli host cells (± 92% and ± 60% after 100 generations, respectively). The PasA antidote of each pas was unable to neutralize the PasB toxin of the other plasmid. The pas proteins of each plasmid autoregulated their own expression as well as that of the pas of the other plasmid. The pas of pTF-FC2 was more effective at repressing the pas operon of pTC-F14 than the pas of pTC-F14 was able to repress itself or the pas of pTF-FC2. This increased efficiency was not due to the PasC of pTF-FC2. The effect of this stronger repression was that pTF-FC2 displaced pTC-F14 when the two plasmids were coresident in the same E. coli host cell. Plasmid curing resulted in the arrest of cell growth but did not cause cell death, and plasmid stability was not influenced by the E. coli mazEF genes.
Description
Keywords
amino acid, antitoxin, bacterial toxin, PasA antitoxin, PasB toxin, unclassified drug, article, autoregulation, bacterial gene, cell death, cell growth, Escherichia coli, evolution, gene expression regulation, gene interaction, gene repression, genetic stability, host range, nonhuman, nucleotide sequence, plasmid, plasmid addiction system, priority journal, Antidotes, Bacterial Proteins, Bacterial Toxins, Base Sequence, Conjugation, Genetic, DNA Helicases, DNA-Binding Proteins, Escherichia coli, Evolution, Molecular, Gene Expression Regulation, Bacterial, Molecular Sequence Data, Operon, Plasmids, Proteins, Sequence Analysis, DNA, Trans-Activators, Bacteria (microorganisms), broad host range plasmids, Escherichia coli, Negibacteria
Citation
Journal of Bacteriology
186
7
186
7