Studies ofSchizosaccharomyces pombeTFIIE indicate conformational and functional changes in RNA polymerase II at transcription initiation.

The general transcription factor TFIIE plays essential roles in transcription by RNA polymerase II (PolII). Despite recent progress, the elucidation of its precise mechanisms including biological functions awaits further characterization. We report the isolation and characterization ofSchizosaccharomyces pombeTFIIE (spTFIIE). Like human and other eukaryotic TFIIE proteins, spTFIIE consists ofα andβ subunits and the genes encoding both subunits are essential for viability. Chromatin immunoprecipitation assays demonstrated that spTFIIE localizes to promotersin vivo. Mutational analysis of the C-terminal basic helix-loop region of TFIIEβ, which is involved in the transition from transcription initiation to elongation, revealed that transcription-defective mutants affected in this region are also cold sensitive. The spTFIIEβ subunit binds both spTFIIEβ and spTFIIEα but spTFIIEα binds only spTFIIEβ. These results indicate that TFIIE forms anα₂β₂ heterotetramer in which twoαβ heterodimers are connected viaβ subunits. Further analysis of binding specificities showed that spTFIIEβ binds the Rpb2 and Rpb12 subunits of PolII, whereas spTFIIEα predominantly binds Rpb5, which is located at the clamp region and changes conformation upon transcription initiation. [ABSTRACT FROM AUTHOR]