[Excision repair of plasmid in competent Escherichia coli cells].
Excision repair in calcium-treated cells E. coli K12, which are usually used for transformation, was studied. A great decrease in excision repair capacity of calcium-treated cells compared to that of untreated cells was observed when cells were incubated in buffer. Analysis of excision repair in E. coli cells were performed by following methods: (1) plasmid DNA, treated in vivo with 8-methoxypsoralen (8-MOP) plus light (lambda less than 310 nm) was transformed into calcium-treated E. coli cells and excision of 8-MOP monoadducts was measured by method of repeated irradiation; (2) plasmid DNA, treated with 8-MOP plus light or irradiated at 254 nm in calcium-treated cells, was isolated, and conversion of supercoil plasmid DNA to relaxing form was detected by agarose gel electrophoresis. Excision repair capacity of calcium-treated cells was restored to the level of that of intact cells after the addition of carbon nutrients (L-broth, glucose). It is supposed that decrease in excision repair capacity of calcium-treated cells is due to the limitation of the intracellular energy sources (probably, ATP), required for the formation of single-stranded nicks in damaged DNA by UVR ABC--endonuclease.
D002118:Calcium / Q000494:pharmacology*; D004260:DNA Repair; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D008027:Light; D008730:Methoxsalen / Q000494:pharmacology; D010957:Plasmids / Q000187:drug effects* / Q000528:radiation effects; D014466:Ultraviolet Rays
D002118:Calcium; D008730:Methoxsalen
Ekstsizionnaia reparatsiia plazmid v kompetentnykh kletkakh Escherichia coli.