High-throughput evaluation of T7 promoter variants using biased randomization and DNA barcoding

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Cis-regulatory elements (CREs) are crucial for controlling gene expression.
• Understanding CRE function is vital for biological research.
• Existing methods for analyzing CRE mutations can be low-throughput.

Purpose of the Study:

• To develop an improved, high-throughput method for analyzing mutant CRE sequences.
• To quantify the transcriptional activity of a large number of CRE variants simultaneously.
• To identify specific sequences within CREs that significantly impact gene regulation.

Main Methods:

• Generating mutant CRE libraries with unique barcodes via biased randomization and PCR.
• Utilizing next-generation sequencing (NGS) to analyze DNA and RNA libraries.
• Quantifying transcriptional activity of thousands of T7 promoter variants.
• Correlating transcriptional activity with protein abundance using in vitro transcription/translation systems.

Main Results:

• Successfully created a randomized T7 promoter library with high coverage for base substitutions (0-5).
• Quantified the transcriptional activity of 7847 T7 promoter variants in a single NGS analysis.
• Identified that bases -9 to -7 are critical for T7 promoter activity, consistent with prior research.
• Demonstrated a strong correlation between CRE variant transcriptional activity and protein output.

Conclusions:

• The developed method provides a simple and high-throughput approach for analyzing CRE mutations.
• This methodology is effective for understanding the impact of CRE variations on transcriptional regulation.
• The findings validate the method's utility and provide insights into T7 promoter function.