Publication Date:
2010-12-18
Description:
Changes in gene regulatory networks are a major source of evolutionary novelty. Here we describe a specific type of network rewiring event, one that intercalates a new level of transcriptional control into an ancient circuit. We deduce that, over evolutionary time, the direct ancestral connections between a regulator and its target genes were broken and replaced by indirect connections, preserving the overall logic of the ancestral circuit but producing a new behaviour. The example was uncovered through a series of experiments in three ascomycete yeasts: the bakers' yeast Saccharomyces cerevisiae, the dairy yeast Kluyveromyces lactis and the human pathogen Candida albicans. All three species have three cell types: two mating-competent cell forms (a and alpha) and the product of their mating (a/alpha), which is mating-incompetent. In the ancestral mating circuit, two homeodomain proteins, Mata1 and Matalpha2, form a heterodimer that directly represses four genes that are expressed only in a and alpha cells and are required for mating. In a relatively recent ancestor of K. lactis, a reorganization occurred. The Mata1-Matalpha2 heterodimer represses the same four genes (known as the core haploid-specific genes) but now does so indirectly through an intermediate regulatory protein, Rme1. The overall logic of the ancestral circuit is preserved (haploid-specific genes ON in a and alpha cells and OFF in a/alpha cells), but a new phenotype was produced by the rewiring: unlike S. cerevisiae and C. albicans, K. lactis integrates nutritional signals, by means of Rme1, into the decision of whether or not to mate.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254258/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254258/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Booth, Lauren N -- Tuch, Brian B -- Johnson, Alexander D -- R01 GM037049/GM/NIGMS NIH HHS/ -- R01 GM037049-26/GM/NIGMS NIH HHS/ -- R01 GM037049-27/GM/NIGMS NIH HHS/ -- England -- Nature. 2010 Dec 16;468(7326):959-63. doi: 10.1038/nature09560.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21164485" target="_blank"〉PubMed〈/a〉
Keywords:
Candida albicans/cytology/*genetics/metabolism/physiology
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*Evolution, Molecular
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Fungal Proteins/genetics/metabolism
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Gene Expression Profiling
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*Gene Expression Regulation, Fungal/genetics
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Genes, Fungal/genetics
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Homeodomain Proteins/genetics/metabolism
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Kluyveromyces/cytology/*genetics/physiology
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Models, Biological
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Phenotype
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Protein Precursors/genetics/metabolism
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Repressor Proteins/genetics/metabolism
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Saccharomyces cerevisiae/cytology/*genetics/metabolism/physiology
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Saccharomyces cerevisiae Proteins/genetics/metabolism
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Transcription, Genetic/*genetics
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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