Evolution of gene auto-regulation in the presence of noise.

摘要: Auto-regulatory negative feedback loops, where the protein expressed from a gene inhibits its own expression are common network motifs within cells. We investigate when will introducing mechanism be beneficial in terms of increasing fitness function that is given by probability maintaining numbers above critical threshold. Our results show existence trade-off as decreases average number molecules driving this closer to threshold (which fitness) but also reduces stochastic fluctuations around mean increases fitness). provide analytical conditions under which can evolve, is, increase fitness. Analyses these feedbacks more likely evolve (i) source noise population extrinsic (i.e. caused exogenous signals network) and not intrinsic randomness associated with mRNA/protein degradation); (ii) dynamics signal causing slower than dynamics; (iii) level for low. degradation rates factors determining whether transcription or translational should evolve. In particular, mRNA half-life much shorter protein's half-life, then transcriptional On other hand, preferred stable mRNAs have long half-lifes.