Counter-selectable markers: Difference between revisions
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#Single gene responsible for selection | #Single gene responsible for selection | ||
#*enables easier determination of mutations responsible for phenotype | #*enables easier determination of mutations responsible for phenotype | ||
#*for instance, a system where a | #*for instance, a system where a constitutive repressor turned off a toxin could accumulate mutations in either the repressor or the toxin | ||
#Strong selective pressure | #Strong selective pressure | ||
#*less false positives | #*less false positives | ||
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#thyA (trimethoprim) | #thyA (trimethoprim) | ||
#pheS (p-chlorophenylalanine) | #pheS (p-chlorophenylalanine) | ||
#*Relaxed substrate specificity mutant of phenylalanine tRNA transferase that will incorporate p-chlorophenylalanine into proteins, killing the cell | |||
#?(phage) | #?(phage) | ||
#*probably >1 gene can confer resistance? | #*probably >1 gene can confer resistance? | ||
Revision as of 18:47, 8 May 2006
Desired Characteristics
- Short sequence
- shorter markers will enable cheaper synthesis of codon variants with different stabilities.
- Single gene responsible for selection
- enables easier determination of mutations responsible for phenotype
- for instance, a system where a constitutive repressor turned off a toxin could accumulate mutations in either the repressor or the toxin
- Strong selective pressure
- less false positives
- On the chromosome?
- Not sure how mutations on a plasmid differ...
Candidates
gene(selection condition)
- lacY (t-o-nitrophenyl-B-D-galactopyranoside)
- thyA (trimethoprim)
- pheS (p-chlorophenylalanine)
- Relaxed substrate specificity mutant of phenylalanine tRNA transferase that will incorporate p-chlorophenylalanine into proteins, killing the cell
- ?(phage)
- probably >1 gene can confer resistance?
- previous work (Novick/Szilard) has mapped mutation rates confering T1 resistance in chemostats.
- pyrF (5FoA)
- Jeff has ordered synthesized/BB'd
- in pyrF- strains can be selected on medium w/o Uracil, so can be selected and coutner-selected.
- sacB
- tet?
- others???
