The DNA sequence at the T7 C promoter.

Area of Science:

• Molecular Biology
• Genetics
• Virology

Background:

• Bacterial RNA polymerase interactions with viral DNA are crucial for gene expression.
• T7 phage gene 1 regulation involves specific promoter elements.
• Previous work identified promoter C near T7 gene 1, with a proposed TACA sequence at the initiation site.

Purpose of the Study:

• To identify and characterize restriction fragments of T7 DNA that selectively bind E. coli RNA polymerase.
• To elucidate the sequence and functional role of the C promoter in T7 DNA.

Main Methods:

• Selective binding assays using E. coli RNA polymerase and T7 DNA restriction fragments.
• DNA sequencing of the smallest RNA polymerase-binding fragment from the C promoter region.
• In vitro RNA synthesis and sequencing using identified fragments.

Main Results:

• Identified T7 DNA restriction fragments that selectively bind E. coli RNA polymerase.
• Sequenced the smallest binding fragment, revealing a promoter-like sequence near the proposed TACA site.
• Sequenced in vitro synthesized RNA, confirming it corresponds to the sequence downstream of the C promoter.
• The C promoter sequence significantly differs from T7 promoters A1, A2, and A3.

Conclusions:

• The identified promoter-like sequence in T7 DNA binds E. coli RNA polymerase.
• The C promoter's unique sequence and location suggest a specific role in T7 phage infection.
• Further investigation into the C promoter's function in T7 biology is warranted.