During transcription in eukaryotes, RNA polymerase II requires a set of general transcription factors (GTFs) to assemble at the promoter. Which GTF is responsible for recognizing and binding the TATA box sequence in the promoter, and which subunit of this factor directly contacts DNA?

• A TFIIA; the TBP subunit contacts the TATA box through its saddle-shaped beta-sheet
• B TFIID; the TATA-binding protein (TBP) subunit directly contacts the TATA box ✓
• C TFIIH; the XPB helicase subunit unwinds DNA at the TATA box
• D TFIIB; it bridges the TATA box and RNA Pol II

Explanation

TFIID is the first general transcription factor to bind the promoter. Its TBP (TATA-binding protein) subunit directly recognizes and binds the TATA box via its C-terminal saddle-shaped domain, inserting beta-sheets into the minor groove and inducing a ~90° bend in the DNA. TBP binding nucleates assembly of the remaining GTFs (TFIIA, TFIIB, TFIIF, RNA Pol II, TFIIE, TFIIH) into the pre-initiation complex.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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