Interconversion between active and inactive TATA-binding protein transcription complexes in the mouse genome.

Area of Science:

• Molecular Biology
• Gene Regulation
• Biochemistry

Background:

• TATA binding protein (TBP) is essential for RNA polymerase II (Pol II) transcription.
• Mammalian B-TFIID complex, comprising TBP and B-TAF1, has an unclear role in transcription regulation.

Purpose of the Study:

• To investigate the function of mammalian B-TFIID in transcription.
• To identify TBP mutations affecting B-TFIID complex formation and its regulatory role.

Main Methods:

• Utilized a conditional TBP knockout mouse cell system.
• Employed tandem affinity purification and mass spectrometry to identify TBP interaction mutants.
• Performed transcriptome and ChIP-seq analyses to assess gene expression and TBP/Pol II recruitment.

Main Results:

• Identified two TBP mutations (R188E, K243E) disrupting TBP-BTAF1 interaction and B-TFIID formation.
• Loss of B-TFIID did not globally alter gene expression but modulated TBP/Pol II recruitment at specific promoters.
• Discovered a partial preinitiation complex involving B-TFIID that primes promoters for Pol II recruitment.

Conclusions:

• Propose a novel mechanism where B-TFIID primes mammalian promoters for transcription.
• B-TFIID acts as a regulatory factor, influencing the assembly of the full preinitiation complex and subsequent gene activation.