Keane, Orla M. and Toft, Christina and Carretero-Paulet, Lorenzo and Jones, Gary W. and Fares, Mario A. (2014) Preservation of Genetic and Regulatory Robustness in Ancient Gene Duplicates of Saccharomyces cerevisiae. Genome Research, 14. pp. 1-29. ISSN 1088-9051

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Abstract

Biological systems remain unperturbed (are robust) in the face of certain genetic and environmental challenges. Robustness allows exploration of ecological adaptations. It is unclear what factors contribute to increasing robustness. Gene duplication has been considered to increase genetic robustness through functional redundancy, accelerating the evolution of novel functions. However, recent findings have brought the link between duplication and robustness into question. In particular, it remains elusive whether ancient duplicates still bear potential for innovation through preserved redundancy and robustness. Here we have investigated this question by evolving the yeast Saccharomyces cerevisiae for 2,200 generations under conditions allowing the accumulation of deleterious mutations and put, for the first time, mechanisms of mutational robustness to test. S. cerevisiae declined in fitness along the evolution experiment but this decline decelerated in later passages suggesting functional compensation of mutated genes. We resequenced 28 genomes from experimentally evolved S. cerevisiae lines and found that mutations accumulated more in duplicates than in singletons, and this enrichment of mutations was found mainly in genes that originated through small-scale duplications. Genetically interacting duplicates showed similar selection signatures and fixed more amino acid replacing mutations than expected. Regulatory robustness of duplicates was supported in our experiment by a larger enrichment for mutations at the promoters of duplicates than at those of singletons. Analyses of yeast gene expression under different environmental conditions showed larger variation in duplicate’s expression than that of singletons under a range of stress conditions, sparking the idea that regulatory robustness allowed exploration of a wider range of phenotypic responses to environmental stresses, hence faster adaptations. Our data provide strong support for the persistence of genetic and regulatory robustness in ancient duplicates and for the role of this robustness in the evolution of adaptations to various stresses.

Item Type:	Article
Additional Information:	This article is made available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/. We thank Dr. Pablo Labrador for very valuable discussion on the manuscript. This study has been supported by a grant from the Spanish Ministerio de Economía y Competitividad (BFU2009- 12022), and another grant from the Science Foundation Ireland (12/IP/1673) to MAF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. CT was funded by an EMBO long-term postdoctoral fellowship (Reference: ALTF730-2011). We would finally like to thank the anonymous reviewers who have contributed to improving this manuscript.
Keywords:	Preservation; Genetic robustness; Regulatory robustness; Ancient Gene Duplicates; Saccharomyces cerevisiae;
Academic Unit:	Faculty of Science and Engineering > Biology
Item ID:	6018
Identification Number:	https://doi.org/10.1101/gr.176792.114
Depositing User:	Dr. Gary Jones
Date Deposited:	10 Apr 2015 15:27
Journal or Publication Title:	Genome Research
Publisher:	Cold Spring Harbour Laboratory Press
Refereed:	Yes
Funders:	Science Foundation Ireland (SFI)
URI:	http://genome.cshlp.org
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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