| Abstract: |
The RNA polymerase II carboxy-terminal domain (CTD) consists of tandem Y1S2P3T4S5P6S7 repeats. Dynamic remodeling of the CTD, especially its serine phosphorylation pattern, conveys informational cues about the transcription apparatus to a large ensemble of CTD-binding proteins. Our genetic dissection of fission yeast CTD function provides insights to the " CTD code." Two concepts stand out. First, the Ser2 requirement for transcription during sexual differentiation is bypassed by subtracting Ser7, signifying that imbalance in the phosphorylation array, not absence of a phospho-CTD cue, underlies a CTD-associated pathology. Second, the essentiality of Ser5 for vegetative growth is circumvented by covalently tethering mRNA capping enzymes to the CTD, thus proving that capping enzyme recruitment is a chief function of the Ser5-PO4 mark. This illustrates that a key " letter" in the CTD code can be neutralized by delivering its essential cognate receptor to the transcription complex via an alternative route. © 2011 Elsevier Inc. |
