Congruence between noise and plasticity in protein expression

Area of Science:

• Molecular Biology
• Systems Biology
• Genetics

Background:

• Gene expression variability arises from mutations, environmental changes, and molecular noise.
• Interdependence exists between different types of variability, but the relationship between plasticity and noise is debated.
• Previous studies faced methodological discrepancies by measuring plasticity at the mRNA level and noise at the protein level.

Purpose of the Study:

• To empirically investigate the relationship between noise and plasticity in gene expression at the protein level.
• To determine if gene essentiality influences the coupling between noise and plasticity.
• To resolve methodological discrepancies in previous studies by measuring both parameters from the same dataset.

Main Methods:

• Utilized flow cytometry to measure protein expression in Escherichia coli.
• Quantified both noise (variability under constant conditions) and plasticity (variability in response to environmental changes) from the same dataset.
• Analyzed protein expression data for both essential and nonessential genes.

Main Results:

• Essential genes displayed lower levels of both noise and plasticity compared to nonessential genes.
• A positive correlation between noise and plasticity was observed in nonessential genes.
• Essential genes did not show a significant correlation between noise and plasticity.

Conclusions:

• Provides empirical evidence for essentiality-dependent coupling between noise and plasticity in protein expression.
• Highlights that the relationship between gene expression noise and plasticity is influenced by gene essentiality.
• Suggests a distinct organization of variability types in essential versus nonessential genes.