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Abstract title Mode of gene regulation – activation or repression – theoretically studied from crosstalk perspective
Author Rok Grah, IST Austria, Klosterneuburg, Austria (Presenting Author)
Topic 19 Evolution of gene expression regulation
Abstract text

Gene regulation can take two forms: some genes are inactive by default and become active following interaction with an activator(positive regulation), others are active by default and a repressor is needed for inactivation(negative regulation).How did these two regulation types evolve?It was previously suggested that high-demand(often used) genes evolved positive regulation while low-demand(rarely used) genes evolved negative one. However,in this strategy the default unregulated state of both high and low-demand genes is the less common state,making pervasive use of regulatory proteins necessary. The specificity of transcription factor(TF)-DNA interactions is known to be limited,potentially leading to transcriptional crosstalk,if a transcription factor regulates a non-cognate gene or fails to regulate a cognate one.Here we study how the usage of different regulatory strategies affects crosstalk levels.We compare crosstalk in the aforementioned “busy” strategy to crosstalk in an opposite “idle” one,in which the default unregulated state of the genes is the more commonly used.We employ a mathematical model for crosstalk between many TFs and many genes.We find that in large part of the parameter regime crosstalk increases with the number of transcription factor species present.We conclude that the “idle” strategy which is more economical in transcription factor usage yields lower crosstalk than the “busy” one.