Sequence-specific DNA binding by the S. shibatae TFIIB homolog, TFB, and its effect on promoter strength

Previous studies have established that Archaea possess a homolog of the eukaryotic basal transcription factor TFIIB, termed TFB, that functions together with the archaeal TATA-binding protein (TBP) to direct transcription by RNA polymerase. Here, we analyze the strong S. shibatae viral (SSV) T6 promoter and show that the region of DNA immediately upstream of the TATA-like A box influences promoter strength. When placed upstream of the much weaker rRNA promoter, this sequence makes it as strong as the T6 promoter. By using a combination of approaches, we show that S. shibatae TFB mediates sequence-specific interactions with DNA flanking the A box. Thus, sequence-specific DNA recognition by TFB and TBP are codeterminants of promoter strength in Archaea.