TATA-Binding Protein (TBP)

TATA-binding protein (TBP) is a universal transcription factor that specifically recognizes and binds to the TATA box in the core promoter region of many eukaryotic genes. TBP is essential for the initiation of transcription by RNA polymerase II, and also plays roles in transcription by RNA polymerase I and III.

Key Features:

Function:

1. DNA Binding:
   • TBP recognizes the TATA box sequence (e.g., TATAAA).
   • It binds to the minor groove of DNA, causing a sharp bend (~80°) in the DNA helix.
   • This bending helps melt or open the DNA, preparing it for transcription.
2. Recruitment of Transcription Machinery:
   • TBP is part of the TFIID complex, which also includes TBP-associated factors (TAFs).
   • After binding the TATA box, TBP helps recruit other general transcription factors (TFIIA, TFIIB, TFIIE, TFIIF, TFIIH) and RNA polymerase II to form the pre-initiation complex (PIC).
3. Initiation of Transcription:
   • Once the PIC is assembled, RNA polymerase II can initiate RNA synthesis at the transcription start site.

TBP in Other Transcription Systems:

Biological Importance:

• Essential for gene expression in all eukaryotic cells.
• Plays a central role in positioning the transcription machinery correctly at the start of genes.
• Involved in development, cell differentiation, and response to environmental signals.

Clinical Relevance:

• TBP mutations or dysregulation are associated with diseases such as:
  • Spinocerebellar ataxia 17 (SCA17) – a neurodegenerative disorder caused by TBP gene mutation.
• TBP function is a target of viral and cellular regulatory proteins that control transcription levels.

Summary Table: