Systematic Quantification of Sequence and Structural Determinants Controlling mRNA stability in Bacterial Operons.

Area of Science:

• Synthetic biology
• Molecular biology
• Bacterial genetics

Background:

• Messenger RNA (mRNA) degradation is crucial for gene expression regulation.
• Factors controlling mRNA decay rates in bacterial operons are not fully understood.
• Understanding mRNA stability is essential for engineering genetic systems.

Purpose of the Study:

• To identify sequence and structural determinants of mRNA stability in bacterial operons.
• To develop a learn-by-design approach for controlling mRNA decay rates.
• To create biophysical models and design rules for predictable mRNA stability.

Main Methods:

• Designed, constructed, and characterized 82 synthetic operons in Escherichia coli.
• Systematically varied RNase binding sites, translation initiation, and termination efficiencies.
• Measured mRNA levels using reverse transcription quantitative polymerase chain reaction (RT-qPCR).

Main Results:

• Introducing single-stranded RNA in 5' untranslated regions (UTRs) decreased mRNA levels up to 9.4-fold.
• Lowering translation initiation rates reduced mRNA levels up to 11.8-fold.
• RNase binding sites in intergenic regions and 3' UTR modifications had minimal impact on upstream mRNA levels.

Conclusions:

• Translation rates and 5' UTR structures are major determinants of bacterial mRNA stability.
• Developed validated biophysical models for ribosome protection and RNase activity.
• Formulated design rules for rationally controlling mRNA stability and engineering genetic systems.