During transcription, RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is it's DNA-binding sequence?

Options

A. CACC
B. TATA
C. TTAA
D. AATT

Answer

**Step-by-Step Solution:**

1. **Understanding Transcription**: Transcription is the process where a specific segment of DNA is copied into RNA. This process is crucial for gene expression.

2. **Identifying the Role of RNA Polymerase**: RNA polymerase is the enzyme responsible for synthesizing RNA from the DNA template. It binds to specific regions of the DNA called promoters.

3. **Recognizing the Promoter Sequence**: Promoters are specific DNA sequences where RNA polymerase binds to initiate transcription. One of the most common promoter sequences in eukaryotic cells is known as the TATA box.

4. **Defining the TATA Box**: The TATA box is a conserved sequence found in many promoters, typically consisting of the nucleotide sequence TATA. It is located about 25-30 base pairs upstream of the transcription start site.

5. **Selecting the Correct Answer**: Given the options (CACA, CACC, TATA, TTA, AATT), the TATA box is the correct DNA-binding sequence for RNA polymerase during transcription.

6. **Final Answer**: Therefore, the DNA-binding sequence for RNA polymerase holoenzyme at the gene promoter is **TATA**.

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