Environmental dependence of genetic constraint

de Vos, Marjon and Poelwijk, Frank J and Battich, Nico and Ndika, Joseph D T and Tans, Sander J (2013) Environmental dependence of genetic constraint. PLoS Genetics, 9 (6). Article No. e1003580. ISSN 1553-7404

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Abstract

The epistatic interactions that underlie evolutionary constraint have mainly been studied for constant external conditions. However, environmental changes may modulate epistasis and hence affect genetic constraints. Here we investigate genetic constraints in the adaptive evolution of a novel regulatory function in variable environments, using the lac repressor, LacI, as a model system. We have systematically reconstructed mutational trajectories from wild type LacI to three different variants that each exhibit an inverse response to the inducing ligand IPTG, and analyzed the higher-order interactions between genetic and environmental changes. We find epistasis to depend strongly on the environment. As a result, mutational steps essential to inversion but inaccessible by positive selection in one environment, become accessible in another. We present a graphical method to analyze the observed complex higher-order interactions between multiple mutations and environmental change, and show how the interactions can be explained by a combination of mutational effects on allostery and thermodynamic stability. This dependency of genetic constraint on the environment should fundamentally affect evolutionary dynamics and affects the interpretation of phylogenetic data.

Item Type: Article
DOI: 10.1371/journal.pgen.1003580
Subjects: 500 Science > 570 Life sciences; biology
Research Group: Bollenbach Group
SWORD Depositor: Sword Import User
Depositing User: Sword Import User
Date Deposited: 04 Jan 2016 16:13
Last Modified: 05 Sep 2017 14:21
URI: https://repository.ist.ac.at/id/eprint/412

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