Genetic Redundancies Enhance Information Transfer in Noisy Regulatory Circuits
Fig 4
Extrinsic noise and cross-talk among redundant copies limit information transfer.
(A) Input/output distributions depicting information transfer. Correlation among individual gene responses due to extrinsic noise or cross-talk reduces the response alphabet, and generates a less linear averaged stimulus-response profile (black curve, see Fig 2A for comparison). (B) Dependence of mutual information (MI) with the strength of extrinsic noise (Materials and Methods). Relative MI is with respect to absence of extrinsic noise. For this plot, we considered a system of N = 5 bistable units implemented with positive feedback. The inset shows a direct comparison between N = 1 and N = 5, emphasizing that MI increases with N. (C) Dependence of MI with the degree of cross-talk for the same regulatory system, but now constituted by N = 2 units. Relative MI is with respect to the situation without cross-talk. The inset presents the marginal probability distribution of gene expression of one unit (y1) in the absence and presence of cross-talk (parameterized by ε = 0 and ε = 0.01, respectively; see Materials and Methods) for the mean value of the input signal (x). Note that when the units are coupled, gene expression becomes unimodal (dashed curve).