RESUMO
Gene duplication stimulates evolutionary innovation as the resulting paralogs acquire mutations that lead to sub- or neofunctionalization. A comprehensive in silico analysis of paralogs in Saccharomyces cerevisiae reveals that duplicates of cell-surface and subtelomeric genes also undergo ectopic recombination, which leads to new chimaeric alleles. Mimicking such intergenic recombination events in the FLO (flocculation) family of cell-surface genes shows that chimaeric FLO alleles confer different adhesion phenotypes than the parental genes. Our results indicate that intergenic recombination between paralogs can generate a large set of new alleles, thereby providing the raw material for evolutionary adaptation and innovation.
Assuntos
Duplicação Gênica/genética , Lectinas de Ligação a Manose/genética , Recombinação Genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Alelos , Adesão Celular/genética , Evolução Molecular , Regulação Fúngica da Expressão Gênica , Variação Genética , Mutação , Fenótipo , Homologia de Sequência de AminoácidosRESUMO
Yeast cells produce various volatile metabolites that are key contributors to the pleasing fruity and flowery aroma of fermented beverages. Several of these fruity metabolites, including isoamyl acetate and ethyl acetate, are produced by a dedicated enzyme, the alcohol acetyl transferase Atf1. However, despite much research, the physiological role of acetate ester formation in yeast remains unknown. Using a combination of molecular biology, neurobiology, and behavioral tests, we demonstrate that deletion of ATF1 alters the olfactory response in the antennal lobe of fruit flies that feed on yeast cells. The flies are much less attracted to the mutant yeast cells, and this in turn results in reduced dispersal of the mutant yeast cells by the flies. Together, our results uncover the molecular details of an intriguing aroma-based communication and mutualism between microbes and their insect vectors. Similar mechanisms may exist in other microbes, including microbes on flowering plants and pathogens.
Assuntos
Drosophila/fisiologia , Proteínas/genética , Saccharomyces cerevisiae/genética , Olfato , Acetatos/farmacologia , Animais , Antenas de Artrópodes/efeitos dos fármacos , Antenas de Artrópodes/fisiologia , Drosophila/efeitos dos fármacos , Deleção de Genes , Odorantes , Saccharomyces cerevisiae/químicaRESUMO
The emergence of new genes throughout evolution requires rewiring and extension of regulatory networks. However, the molecular details of how the transcriptional regulation of new gene copies evolves remain largely unexplored. Here we show how duplication of a transcription factor gene allowed the emergence of two independent regulatory circuits. Interestingly, the ancestral transcription factor was promiscuous and could bind different motifs in its target promoters. After duplication, one paralogue evolved increased binding specificity so that it only binds one type of motif, whereas the other copy evolved a decreased activity so that it only activates promoters that contain multiple binding sites. Interestingly, only a few mutations in both the DNA-binding domains and in the promoter binding sites were required to gradually disentangle the two networks. These results reveal how duplication of a promiscuous transcription factor followed by concerted cis and trans mutations allows expansion of a regulatory network.