Lys2/+ selection with aAA?

[Ellie Harrison]

Hi all,

I am attemping to use alpha aminoadipate media to kill off both LYS2/LYS2 homozygote AND LYS2/lys2 heterozygote diploids (so only lys2/lys2 survives) in a selection experiment.  Annoyingly the LYS2/lys2 heterozygote does not have enough activity to produce the toxic products which kill off the WT when using aminoadipate in the recommended media- ie. minimal media w/ 2g/L aAA plus lysine.  

Does anyone know of a concentration which selects for ONLY the mutant homozygote and is toxic to the heterozygote (or if this is in fact possible!)

thanks for your help

Ellie