Adaptive evolution of Transcription Factors in European and wine yeast

University essay from Södertörns högskola/Institutionen för livsvetenskaper

Abstract:

The mutability of transcription factors (TF) is thought to be of high importance for the evolutionary change of living organisms. Transcription factors, coactivators, coregulators, kinases, chromatin remodelers conditional factors and other proteins together govern the timing and level of gene expression. About 10% of the genes in the human genome are predicted to be TFs and mutational changes in these genes or in the target regulatory sequences they bind will potentially give rise to evolutionary advantages or malfunctions for the organism. Recent research has suggested that the parts of the transcription factors that are not structurally defined in solution, so called intrinsically disordered regions (IDRs), have a higher potential for evolutionary diversification than more structurally rigid regions. This suggests that these domains that earlier have been considered mostly unimportant may have an important potential for evolutionary diversification. This project aimed to further evaluate evidence supporting the hypothesis that variable-structured domains in transcription factors are of significant importance for functional diversification. This was be done by comparing the rate of synonymous and non-synonymous genetic variation in the coding regions of 12 selected TFs within a highly conserved clade of European wine yeasts and by comparing this variation to divergent phenotypic patterns within the strains. The frequency of non-synonymous mutations was much greater than for synonymous mutations indicating an important role of positive selection acting on these TFs during diversification of the different strains. No significant connections were discovered between the distribution of DNA variation and phenotypic patterns.

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