| Modification Notes |
Normal transcription of a large number of genes requires the S. cerevisiae SAGA complex which has three core subunits, Spt7, Spt20 and Ada1 (1). Spt7 is crucial for controlling the levels of the other core subunits and assembly of the complex (1). Spt7 is a negatively charged, 1,332 amino acid protein which contains a histone fold required for interaction of the Taf10 subunit of SAGA and a bromodomain found in many transcription factors (1). Spt7 directly associates with Spt8 making it possible for Spt8 to interact with the SAGA complex (1,2). Recruitment of TBP is diminished at a number of SAGA-dependent promoters in ada1delta, spt7delta, and spt20delta null mutants (3). Strains of S. cerevisiae which contain an Spt7 null mutation are viable but grow very slowly and have transcriptional defects at many loci including insertion mutations, Ty elements, the INO1 gene and the MFA1 gene (4,5). These defects are similar to those caused by certain mutations in the SPT15 gene which encodes the TATA binding protein (TBP), indicating that the Spt7 protein plays an important role in transcription initiation in vivo (5). |
