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Effect of Rec mutations on the activity of colicinogenic factors
Abstract:
The effect of two Rec(-) mutations (AB2463 and JC1553) on the ability of a cell to accept, maintain, and express the colicinogenic factors ColE(1), ColE(2), and ColV was examined in Escherichia coli. These mutations had no observable effect on the colicinogenic properties of the ColV factor, but prevented the spontaneous and induced production of colicins E(1) and E(2) which are determined by the ColE(1) and ColE(2) factors, respectively. The two Rec(-) mutations had no apparent effect on the ability of the cells to acquire, maintain, or transfer the ColE(1) and ColE(2) factors. These mutations did not affect the expression of immunity by any of the three Col factors. ColE(1) and ColE(2) were also shown to be indirectly induced by mating F(-) cells carrying these Col factors with ultraviolet-irradiated, non-colicinogenic, Hfr and F(+) cells. Indirect induction of colicin production occurred when either an irradiated F(+) Rec(+) or F(+) Rec(-) strain was employed as the donor strain.
Insights
Rec(-) mutations in Escherichia coli prevent colicin E(1) and E(2) production but do not affect colicin V factor properties or plasmid maintenance. These mutations impact spontaneous and induced colicin expression.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Colicinogenic factors (Col factors) are plasmids in Escherichia coli that confer the ability to produce colicins, a class of bacteriocins.
- Rec(-) mutations affect DNA repair mechanisms, potentially influencing plasmid stability and gene expression.
Purpose of the Study:
- To investigate the impact of Rec(-) mutations on the acceptance, maintenance, and expression of ColE(1), ColE(2), and ColV factors in Escherichia coli.
- To determine if Rec(-) mutations affect colicin production, plasmid transfer, or immunity conferred by these factors.
Main Methods:
- Utilizing two specific Rec(-) mutant strains (AB2463 and JC1553) of Escherichia coli.
- Examining the effects of these mutations on cells harboring ColE(1), ColE(2), and ColV factors.
- Assessing spontaneous and induced colicin production, plasmid acquisition, maintenance, transfer, and immunity expression.
Main Results:
- Rec(-) mutations did not affect the colicinogenic properties of the ColV factor.
- These mutations abolished spontaneous and induced production of colicins E(1) and E(2).
- Rec(-) mutations did not impair the ability of cells to acquire, maintain, or transfer ColE(1) and ColE(2) factors, nor did they affect immunity expression.
Conclusions:
- Rec(-) mutations specifically disrupt the production of colicins E(1) and E(2) in Escherichia coli.
- DNA repair pathways are crucial for the expression of certain colicin types, but not for plasmid maintenance or immunity.
- Indirect induction of colicin production can occur through mating with irradiated cells, irrespective of the Rec(-) status of the donor strain.