Orientation of the transcription preinitiation complex in Archaea

The basal transcription machinery of Archaea corresponds to the minimal sub set of factors required for RNA polymerase II transcription in eukaryotes. Using just two factors, Archaea recruit the RNA polymerase to promoters and define the direction of transcription. Notably, the principal determinant for the orientation of transcription is not the recognition of the TATA box by the TATA-box-binding protein. Instead, transcriptional polarity is gove rned by the interaction of the archaeal TFIIB homologue with a conserved mo tif immediately upstream of the TATA box. This interaction yields an archae al preinitiation complex with the same orientation as the analogous eukarya l complex.