Functional Connections between Mediator Components and General Transcription Factors of Saccharomyces cerevisiae

• Published in: The Journal of biological chemistry Vol. 275; no. 47; pp. 37251 - 37256
• Main Authors: Sakurai, Hiroshi, Fukasawa, Toshio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.11.2000; American Society for Biochemistry and Molecular Biology
• Subjects: Base Sequence; Chromatography, Affinity; DNA-Binding Proteins - metabolism; Fungal Proteins - physiology; Gal11 protein; Hrs1 protein; Med2 protein; Med3 protein; Mediator Complex; Molecular Sequence Data; Pgd1 protein; Saccharomyces cerevisiae; Saccharomyces cerevisiae - physiology; Saccharomyces cerevisiae Proteins; TATA-Binding Protein Associated Factors; TATA-Box Binding Protein; TFIIE protein; TFIIH protein; Trans-Activators - physiology; Transcription Factor TFIID; Transcription Factor TFIIH; Transcription Factors - metabolism; Transcription Factors - physiology; Transcription Factors, TFII
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M004364200

The yeast Gal11 protein is an important component of the Mediator complex in RNA polymerase II-directed transcription. Gal11 and the general transcription factor (TF) IIE are involved in regulation of the protein kinase activity of TFIIH that phosphorylates the carboxyl-terminal domain of RNA polymerase II. We have previously shown that Gal11 binds the small and large subunits of TFIIE at two Gal11 domains, A and B, respectively, which are important for normal function of Gal11 in vivo. Here we demonstrate that Gal11 binds directly to TFIIH through domain A in vitro. A null mutation in GAL11 caused lethality of cells when combined with temperature-sensitive mutations in the genes encoding TFIIE or the carboxyl-terminal domain kinase, indicating the presence of genetic interactions between Gal11 and these proteins. Mutational depletion of Gal11 or TFIIE caused inefficient opening of the transcription initiation region, but had no significant effect on TATA-binding protein occupancy of the TATA sequence in vivo. These results suggest that the functions of Gal11 and TFIIE are necessary after recruitment of TATA-binding protein to the TATA box presumably at the step of stable preinitiation complex formation and/or promoter melting. We illustrate genetic interactions between Gal11 and other Mediator components such as Med2 and Pgd1/Hrs1/Med3.