PT  - JOURNAL ARTICLE
AU  - Andrew C. Bergen
AU  - Gerilyn M. Olsen
AU  - Justin C. Fay
TI  - Divergent <em>MLS1</em> promoters lie on a fitness plateau for gene expression
AID  - 10.1101/026427
DP  - 2015 Jan 01
TA  - bioRxiv
PG  - 026427
4099  - http://biorxiv.org/content/early/2015/09/09/026427.short
4100  - http://biorxiv.org/content/early/2015/09/09/026427.full
AB  - Qualitative patterns of gene activation and repression are often conserved despite an abundance of quantitative variation in expression levels within and between species. A major challenge to interpreting patterns of expression divergence is knowing which changes in gene expression affect fitness. To characterize the fitness effects of gene expression divergence we placed orthologous promoters from eight yeast species upstream of malate synthase (MLS1) in Saccharomyces cerevisiae. As expected, we found these promoters varied in their expression level under activated and repressed conditions as well as in their dynamic response following loss of glucose repression. Despite these differences, only a single promoter driving near basal levels of expression caused a detectable loss of fitness. We conclude that the MLS1 promoter lies on a fitness plateau whereby even large changes in gene expression can be tolerated without a substantial loss of fitness.