Recently i came across E. coli RRI strain, its being usually used for plasmid preps.It has carries a recA gene that has been introduced in the parent strain to create RRI. I was suspecting there would be a specific purpose to use this strain for plasmid isolation but could not find a appropriate answer.Can someone shed light on what is the main purpose of using this particular strain.
RR1 is an strain that was built and used in the very early days of molecular biology (1980s) and hence you find it being used primarily in the older literature. I strongly suspect what you are seeing is just historical artifact. It is reasonably normal strain with no special features other than being RecA-. There is probably no special reason for using it and doesn't confer any real advantage over many other strains.
However there are reasons why you might or might not wish to use a recA mutant strain, the advantages being you will get more homogenous plasmid preps (i.e. all monomers instead of a population of dimers, trimers, tetramers etc that you get from a wild type strain). The downside is that RecA mutant strains grow much more slowly than RecA+.
Hey Michael,
Thanks for the reply.As you suggested the RR1 strain might be an old workhorse with a scant number of people looking for it.
However, it seems that parent strain of RR1 is E. coli K-12 HB101 cells which is recA13 mutant (http://openwetware.org/wiki/E._coli_genotypes#HB101) and RR1 is a derivative of it (http://openwetware.org/wiki/E._coli_genotypes#RR1) being recA+.
I suspect its just an interplay between using a recA+ and recA- mutant for specific applications as you already mentioned.
My apologies but I erred in my answer and you are correct. I was relying on memory from 30 years ago and didn't bother double checking. RR1 certainly is HB101 but made RecA plus. The main part of my answer, that there is nothing special about it, however remains true.
- Badges
- Science topic