Streptomycin resistant E.coli via rpsL

Szatmari George szat at ERE.UMontreal.CA
Thu Jan 19 13:43:44 EST 1995

In article <123808730wnr at> Duncan at writes:
>Hi Folks,
>Does anyone know if an rpsL E.coli ie streptomycin resistant is 
>automatically spectinomycin resistant? I  have the Str/Sp gene 
>from Tn7 on a multicopy plasmid (one of the few antibiotic genes that 
>is stable on v.high copy vectors - the others being Amp and Kan) and 
>use spectinomycin 50ug/ml as my selection. Unfortunately I am finding 
>that my normal strains of choice for other applications are rpsL and 
>give a detectable background on spectinomycin plates. I will take the 
>concn up to 200ug/ml which I know the plasmid quite happily copes 
>with and see if that does the trick. However it would be nice to know 
>if rpsL is automatically Sp resistant.
>My mind's made up. Don't confuse me with the facts!

Dear Duncan,

The chromosomal gene for spec resistance is rpsE, which means that
chromosomal strep-resistance does not necessarily mean the strain
is also spec resistant.  We also have a high background problem with
spec-resistant vectors which we haven't quite figured out yet.

George Szatmari
Univ de Montreal

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