Killer gene

Rafael Maldonado rafael at corona
Tue Mar 14 15:12:42 EST 1995

On Fri, 10 Mar 1995, Pekka Rappu wrote:

> 	Is there a gene encoding some kind of protein that kills E. coli
>         either indirectly by activating a poison, for example, or
>         directly?

There are several of them:

1.- sacB, from B. subtilis, works well in E. coli. When expreseed, and in 
the presence od sucrose in the medium, an intermediate is produced that 
kills the cells.

Gay et al. J. Bacteriol. 164, 918-921 (1985)

2.- rpsL (strA). Since streptomycin resistance is recesive, if you use a 
str(r) strain, the expression of a wild-type allele rpsL is lethal in hte 
presence os strep.

Dean, D. Gene 15, 99-102 (1981)

3.- pheS. I think it is a subunit of the phe-tRNA synthetase. Some mutant 
gene is toxic in presence of an analog. Sorry, I don't remember this very 
well and I have no references.

Anyway,  there is a lot of analogs can be used; the expression of some 
genes is lethal in their presence. You may find interesting:  R. 
T. Vinopal. Selectable phenotypes. In "Escherichia coli and Salmonella 
typhimurium celular and molecular Biology". FC Neidhart ed. in chief. 
Vol. 2, pg. 58. Published by ASM (1987). (The Bible of E. coli.)

I hope this helps



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