Rate-limiting steps in transcription dictate sensitivity to variability in cellular components

Area of Science:

• Molecular Biology
• Systems Biology
• Genetics

Background:

• Cell-to-cell variability in molecular components drives diversity in RNA and protein production.
• Inherited cellular components lead to lineage-specific variations in these production dynamics.
• This variability is hypothesized to be dependent on promoter initiation kinetics.

Purpose of the Study:

• To investigate the role of promoter initiation kinetics in cell-to-cell and lineage-to-lineage variability of RNA production.
• To differentiate between transient and constant sources of variability in RNA production.
• To understand how promoter sequences and induction schemes influence transcription variability.

Main Methods:

• Utilized stochastic models to predict the impact of molecular variability on RNA production dynamics.
• Employed single-cell, single-RNA level time-lapse microscopy in Escherichia coli.
• Analyzed independent cell lineages to assess gene activation times and RNA production rates.

Main Results:

• Stochastic models predicted that upstream molecular variability has transient effects, while variability in transcription-controlling molecules has constant effects on RNA production.
• Empirical data revealed lineage-to-lineage variability in gene activation times and mean RNA production rates in E. coli.
• Observed significant differences in variability based on the promoters and inducers used.

Conclusions:

• Cell-to-cell and lineage-to-lineage variability in RNA and protein production are influenced by promoter sequence-dependent and regulated transcription kinetics.
• Differences in rate-limiting transcription steps explain observed variability patterns.
• Findings highlight the regulatory role of promoter characteristics in gene expression variability.