RNA-POLYMERASE-II C-TERMINAL DOMAIN REQUIRED FOR ENHANCER-DRIVEN TRANSCRIPTION

THE RNA polymerase II carboxy-terminal domain (CTD) consists of tandem repeats of the sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser(1-3). The CTD may participate in activated transcription through interaction with a hig h-molecular-weight mediator complex(4-6). Such a role would be consist ent with observations that some genes are preferentially sensitive to CTD mutations(7,8). Here we investigate the function of the mouse RNA polymerase CTD in enhancer-driven transcription. Transcription by alph a-amanitin-resistant CTD-deletion mutants was tested by transient tran sfection of tissue culture cells in the presence of alpha-amanitin in order to inhibit endogenous RNA polymerase II. Removal of most of the CTD abolishes transcriptional activation by all enhancers tested, wher eas transcription from promoters driven by Sp1, a factor that typicall y activates housekeeping genes from positions proximal to the initiati on sites, is not affected. These findings show that the CTD is essenti al in mediating 'enhancer'-type activation of mammalian transcription.