CONTACT WITH A COMPONENT OF THE POLYMERASE-II HOLOENZYME SUFFICES FORGENE ACTIVATION

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.