Mixed messages: how bacteria resolve conflicting signals

Abstract

An elegant new study by Bollenbach and Kishony (2011) in this issue of Molecular Cell shows how bacteria resolve the apparent conflicts created when they face two signals with opposite effects on gene expression.

Figure 1. Gene Regulation Conflicts in Response to Drugs Are Resolved Using Simple Rules

(A) A gene regulatory conflict (right) occurs when a cell is exposed to two drugs that have opposite effects on gene regulation (left, middle). (B) Conflict resolution is approximately represented by a weighted sum of two factors (principal components). The first component represents the response of the gene to changes in growth rate due to the drugs (heat map, left). The second component indicates the magnitude and direction of conflict response as a function of the relative concentrations of drugs A and B (x axis, right) at fixed growth rate (i.e., along the dashed line, left). The shape of these functions differs for each drug combination. However, the expression of any gene at any specific combination of drugs (blue dot) is approximately given by a weighted sum of the two effects (formula, bottom), where the weights are specific to individual genes.