Defining a bacteriophage T4 late promoter: absence of a "-35" region

Area of Science:

• Molecular Biology
• Genetics
• Virology

Background:

• Bacteriophage T4 utilizes distinct promoter classes for temporal gene expression.
• The P23 promoter is crucial for T4 late gene transcription.
• Understanding promoter elements is key to controlling gene expression.

Purpose of the Study:

• To determine the minimal DNA sequence essential for T4 late promoter P23 function.
• To characterize the regulatory requirements of this minimal promoter.

Main Methods:

• Deletion analysis was employed to progressively shorten the P23 promoter sequence.
• A minipromoter derivative (35 bp) was constructed and tested.
• In vitro and in vivo assays were used to assess promoter activity and regulation.

Main Results:

• A 35 bp DNA fragment (from -18 to +17) containing the TATAAATA sequence functions as a T4 late promoter.
• This minipromoter exhibits in vivo transcriptional activity regulated similarly to wild-type P23.
• Late gene transcription regulation was observed, independent of T4 DNA replication.

Conclusions:

• The minimal functional unit of the T4 P23 late promoter is a 35 bp DNA sequence.
• The TATAAATA box is a critical element for P23 function.
• T4 late promoter activity is regulated by specific T4 gene functions, not DNA replication.