Question

Many promoter regions in genes transcribed by eukaryotic RNA polymerase II do not contain a TATA box sequence. However, all three eukaryotic polymerases require TBP for transcription initiation regardless of the presence of a TATA box in the promoter region. What hypothesis might explain why TBP is necessary for transcription from TATA-less promoters
A. The DNA-bending function of TBP cannot be performed by another protein in the general transcription factor complex.
B. TBP is still required for initial recognition of promoter sequences. This protein has an equal affinity for DNA sequences with and without a TATA box.
C. TBP is required for stabilizing the complex as it assembles on the promoter.
D. TBP is required for the catalytic activity of the RNA polymerase.

Answer 1

Answer:

A. The DNA-bending function of TBP cannot be performed by another protein in the general transcription factor complex.

Explanation:

TATA  box sequence binding protein binds to aspecific region on DNA known as TATA Sequence. TATA binding protein binding to the DNA Sequence is necessary because it generates bending of DNA till 80° angle.

BINDING of all transcription factors depends solely upon the binding of TBP directly, that is why TATA binding proteins bonding to DNA is very important for initiation of transcription. Any other protein does not have the capacity of band formation with DNA. Hence, A. the DNA-bending function of TBP cannot be performed by another protein in the general transcription factor complex.