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 th e eukaryotic basal transcription factor TFIIB, termed TFB, that functi ons together with the archaeal TATA-binding protein (TBP) to direct tr anscription by RNA polymerase. Here, we analyze the strong S. shibatae viral (SSV) T6 promoter and show that the region of DNA immediately u pstream of the TATA-like A box influences promoter strength. When plac ed upstream of the much weaker rRNA promoter, this sequence makes it a s 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 TF B and TBP are codeterminants of promoter strength in Archaea.