title: Expression noise facilitates the evolution of gene regulation.
abstract: Although it is often tacitly assumed that gene regulatory interactions are finely tuned, how accurate gene regulation could evolve from a state without regulation is unclear. Moreover, gene expression noise would seem to impede the evolution of accurate gene regulation, and previous investigations have provided circumstantial evidence that natural selection has acted to lower noise levels. By evolving synthetic Escherichia coli promoters de novo, we here show that, contrary to expectations, promoters exhibit low noise by default. Instead, selection must have acted to increase the noise levels of highly regulated E. coli promoters. We present a general theory of the interplay between gene expression noise and gene regulation that explains these observations. The theory shows that propagation of expression noise from regulators to their targets is not an unwanted side-effect of regulation, but rather acts as a rudimentary form of regulation that facilitates the evolution of more accurate regulation.
authors.affiliation: Biozentrum, University of Basel, Basel, Switzerland.
authors.forename: Luise
authors.initials: L
authors.lastname: Wolf
authors.affiliation: Biozentrum, University of Basel, Basel, Switzerland.
authors.forename: Olin K
authors.initials: OK
authors.lastname: Silander
authors.affiliation: Biozentrum, University of Basel, Basel, Switzerland.
authors.forename: Erik
authors.initials: E
authors.lastname: van Nimwegen
mesh_terms: D019020:Directed Molecular Evolution / Q000379:methods; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D005786:Gene Expression Regulation / Q000502:physiology*; D008957:Models, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D012641:Selection, Genetic; D013269:Stochastic Processes
keywords: E. coli; computational biology; evolution; evolutionary biology; gene expression noise; gene regulation; genomics; synthetic biology; systems biology