Yeast TAFIIS in a multisubunit complex required for activated transcription

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Eukaryotic transcription relies on RNA polymerase II and the TFIID complex, comprising TATA-box-binding protein (TBP) and TBP-associated factors (TAFIIS).
• TAFIIS function as coactivators, essential for activated but not basal transcription.
• The conservation of transcription machinery made the absence of identified TAFIIS in yeast puzzling.

Purpose of the Study:

• To identify and characterize yeast homologs of TBP-associated factors (TAFIIS).
• To investigate the role of these factors in activated transcription by RNA polymerase II in yeast.
• To determine the essentiality of these factors for the viability of Saccharomyces cerevisiae.

Main Methods:

• Utilized TBP as a protein-affinity ligand to isolate yeast protein complexes.
• Performed microsequence analysis on isolated complex subunits.
• Cloned genes encoding identified yeast TAFIIS.

Main Results:

• Successfully isolated a multisubunit complex from yeast required for activated RNA polymerase II transcription.
• Identified two subunits of this complex as homologues of known mammalian and Drosophila TAFIIS.
• Found that the genes encoding these two yeast TAFIIS are essential for cell viability.

Conclusions:

• Demonstrated the presence and function of TAFIIS in yeast, analogous to higher eukaryotes.
• Established that activated transcription, mediated by these TAFIIS, is essential for Saccharomyces cerevisiae survival.
• Provided insights into the conserved mechanisms of eukaryotic gene regulation.