Schutz zellfremder DNA vor wirtskontrollierter Restriktion in Bakterienzellen. II. Schutz des Plasmids pSF2124 durch die ocr+ Genfunktion der Bakteriophagen T3 und T7
✍ Scribed by Monika Reuter; D. H. Krüger; D. Scholz; H. A. Rosenthal
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 784 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
Abstract
When restriction‐active Escherichia coli cells (rm) are transformed with the pSF2124 plasmid, a common vector in experimental gene transfer, the efficiency of transformation (e.o.t.) is lowered by 2 orders of magnitude compared with restriction‐negative (rm or rm) recipient cells due to restriction of the pSF2124 DNA by endoR.__Eco__P1.
Preinfection of rm cells with UV‐inactivated ocr^+^ phages (T3, T7, T3__sam__^−^) still able to express their early genes protects the plasmid DNA against restriction by endoR.__Eco__P1: The e.o.t. of rm recipient cells with pSF2124 attains the same high value as that of r^−^m^−^ cells. The specific role of the ocr^+^ gene function was demonstrated by the use of ocr^−^ mutants (T3/R7, T7/ D111): Preinfection with such phage mutants does not increase the e.o.t. of rm cells. An unspecific e.o.t. alteration of restriction‐negative (r^−^m^−^) recipient cells by ocr^+^ or ocr^−^ phages was excluded.
The ocr^−^ gene function can be exploited to protect pSF2124 against DNA restriction. The recipient cells survive the process of phage preinfection and transformation and stably replicate themselves as well as the plasmid DNA.