Network Topology Can Explain Differences in Pleiotropy Between Cis- and Trans-regulatory Mutations.

Area of Science:

• Evolutionary biology
• Genetics
• Systems biology

Background:

• Pleiotropy, the effect of a single mutation on multiple traits, influences mutation fitness.
• Cis-regulatory mutations are hypothesized to be less pleiotropic than trans-regulatory mutations affecting the same gene.
• This suggests cis-regulatory mutations may be less deleterious and more likely to evolve.

Purpose of the Study:

• To test the hypotheses that cis-regulatory mutations are less pleiotropic and less deleterious than trans-regulatory mutations.
• To investigate the role of regulatory network topology in pleiotropy.
• To determine the evolutionary implications of cis- vs. trans-acting mutations.

Main Methods:

• Utilized gene deletion strains of Saccharomyces cerevisiae.
• Analyzed gene expression and fitness data.
• Modeled gene deletions as cis- or trans-regulatory mutations affecting gene expression.

Main Results:

• Confirmed that cis-acting mutations are generally less pleiotropic than trans-acting mutations affecting the same gene.
• Observed this pattern across the majority of genes studied.
• Found that trans-acting deletions tend to be more deleterious than cis-acting deletions.

Conclusions:

• Regulatory network topology helps explain the observed differences in pleiotropy.
• Pleiotropy plays a significant role in the preferential fixation of cis-regulatory alleles.
• Findings support the evolutionary advantage of cis-regulatory mutations.