Ancient transcriptional regulators can easily evolve new pair-wise cooperativity

We investigate how a protein-protein interaction between two ancient transcriptional regulators (a homeodomain and MADS box protein) was gained approximately 200 million years ago in a clade of ascomycete yeasts that includes Saccharomyces cerevisiae. We combine deep mutational scanning of Matα2 with a functional selection for cooperative gene expression and tested millions of possible alternative evolutionary solutions to this interaction interface. Pooled Matα2 mutants were deeply sequenced before and after selection for functional Matα2-Mcm1 interaction. The changes in frequency of each variant allowed us to determine their relative fitness.本研究探究了约2亿年前，在包含酿酒酵母（Saccharomyces cerevisiae）的子囊酵母分支中，两种古老转录调控因子——同源结构域（homeodomain）蛋白与MADS盒蛋白——之间的蛋白质相互作用是如何演化获得的。我们结合针对Matα2的深度突变扫描（deep mutational scanning）与协同基因表达功能筛选，测试了该相互作用界面的数百万种潜在进化替代方案。在针对功能性Matα2-Mcm1相互作用的筛选前后，我们对混合的Matα2突变体进行了深度测序。各变异体的频率变化可用于确定其相对适合度。