The archaeal TFIIEα homologue facilitates transcription initiation by enhancing TATA‐box recognition

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Abstract
Transcription from many archaeal promoters can be reconstituted in vitro using recombinant TATA‐box binding protein (TBP) and transcription factor B (TFB)—homologues of eukaryal TBP and TFIIB—together with purified RNA polymerase (RNAP). However, all archaeal genomes sequenced to date reveal the presence of TFE, a homologue of the α‐subunit of the eukaryal general transcription factor, TFIIE. We show that, while TFE is not absolutely required for transcription in the reconstituted in vitro system, it nonetheless plays a stimulatory role on some promoters and under certain conditions. Mutagenesis of the TATA box or reduction of TBP concentration in transcription reactions sensitizes a promoter to TFE addition. Conversely, saturating reactions with TBP de‐sensitizes promoters to TFE. These results suggest that TFE facilitates or stabilizes interactions between TBP and the TATA box.