Delayed protein synthesis reduces the correlation between mRNA and protein fluctuations

Area of Science:

• Molecular biology
• Systems biology
• Genetics

Background:

• Recent experiments show uncorrelated mRNA and protein levels in single E. coli cells.
• Basic gene expression models predict a correlation between mRNA and protein levels.
• Discrepancies highlight the need for refined theoretical models.

Purpose of the Study:

• To investigate modifications of the basic two-stage gene expression model.
• To explore the impact of translational and reporter maturation delays on mRNA-protein correlations.
• To reconcile theoretical predictions with experimental findings in prokaryotic gene expression.

Main Methods:

• Development and analysis of a modified two-stage gene expression model.
• Inclusion of translational and reporter maturation delays.
• Mathematical modeling of prokaryotic gene expression dynamics.

Main Results:

• The introduction of delay into the two-stage model significantly reduces the cross-correlation between mRNA and protein levels.
• Theoretical correlation coefficients are sensitive to the inclusion of maturation delays.
• A time shift in protein measurements, corresponding to the delay, can increase the observed correlation.

Conclusions:

• Translational and reporter maturation delays are crucial factors in prokaryotic gene expression.
• These delays help explain the lack of correlation between mRNA and protein levels observed experimentally.
• Accounting for delays provides a more accurate theoretical framework for understanding gene expression.