In yeast strains bearing the point mutation called GAL11P (for potenti
ator), certain GAL4 derivatives lacking any classical activating regio
n work as strong activators. The P mutation confers upon GAL11, a comp
onent of the RNA polymerase II holoenzyme, the ability to interact wit
h a portion of the dimerization region of GAL4, The region of GAL11 af
fected by the P mutation is evidently functionally inert in ordinary c
ells, suggesting that this mutation is of no functional significance b
eyond creating an artificial target for the GAL4 dimerization fragment
. From these observations and further analyses of GAL11, we propose th
at a single activator-holoenzyme contact can trigger gene activation s
imply by recruiting the latter to DNA.