An Evolutionarily Conserved Prion-like Element Converts Wild Fungi from Metabolic Specialists to Generalists

摘要

[GAR~+] is a protein-based element of inheritance that allows yeast (Saccharomyces cerevisiae) to circumvent a hallmark of their biology: extreme metabolic specialization for glucose fermentation. When glucose is present, yeast will not use other carbon sources. [GAR~+] allows cells to circumvent this ''glucose repression.'' [GAR~+] is induced in yeast by a factor secreted by bacteria inhabiting their environment. We report that de novo rates of [GAR~+] appearance correlate with the yeast's ecological niche. Evolutionarily distant fungi possess similar epigenetic elements that are also induced by bacteria. As expected for a mechanism whose adaptive value originates from the selective pressures of life in biological communities, the ability of bacteria to induce [GAR~+] and the ability of yeast to respond to bacterial signals have been extinguished repeatedly during the extended monoculture of domestication. Thus, [GAR~+] is a broadly conserved adaptive strategy that links environmental and social cues to heritable changes in metabolism.