title: Divergent MLS1 Promoters Lie on a Fitness Plateau for Gene Expression.
abstract: 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.
authors.affiliation: Molecular Genetics and Genomics Program, Washington University, St. Louis.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Bergen
authors.affiliation: Washington University, St. Louis.
authors.forename: Gerilyn M
authors.initials: GM
authors.lastname: Olsen
authors.affiliation: Department of Genetics, Washington University, St. Louis Center for Genome Sciences and Systems Biology, Washington University, St. Louis jfay@genetics.wustl.edu.
authors.forename: Justin C
authors.initials: JC
authors.lastname: Fay
mesh_terms: D004271:DNA, Fungal / Q000235:genetics; D019143:Evolution, Molecular; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D056084:Genetic Fitness; D008292:Malate Synthase / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation
chemical_list: D004271:DNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008292:Malate Synthase
keywords: MLS1; binding sites.; evolution; expression; yeast