CRISPR-dCas13a system for programmable small RNAs and polycistronic mRNA repression in bacteria

Area of Science:

• Microbiology
• Molecular Biology
• Synthetic Biology

Background:

• Bacterial small RNAs (sRNAs) regulate gene expression in response to environmental stimuli.
• Limited tools exist for systematic engineering of RNA repression in bacteria due to the absence of eukaryotic RNA interference machinery.

Purpose of the Study:

• To develop a novel CRISPR-guided dead Cas13a (dCas13a) system for programmable bacterial sRNA repression.
• To engineer crRNAs for efficient and specific knockdown of target sRNAs.
• To apply this system for discovering new sRNA targets and optimizing bacterial metabolic pathways.

Main Methods:

• Utilized clustered regularly interspaced short palindromic repeats (CRISPR)-guided dCas13a ribonucleoprotein complexes.
• Designed programmable CRISPR RNAs (crRNAs) to target both trans-acting and cis-acting sRNAs.
• Engineered crRNA modules for enhanced repression efficiency and single base-pair mismatch specificity.
• Constructed 102 crRNAs in a biofoundry for screening sRNA targets in Escherichia coli.

Main Results:

• Achieved high knockdown efficiency (92%) with engineered crRNAs.
• Demonstrated single base-pair mismatch specificity for precise targeting.
• Successfully achieved targetable single-gene repression within polycistronic operons.
• Identified novel sRNA targets to improve lycopene production in E. coli.

Conclusions:

• The developed CRISPR-dCas13a system offers a powerful tool for systematic bacterial sRNA discovery.
• This system enables precise fine-tuning of bacterial RNA repression for scientific research and industrial biotechnology.
• Facilitates engineering of bacterial regulatory mechanisms and stress-related phenotypes.