epistasis
Cooper TF, Remold SK, Lenski RE & Schneider D 2008 Expression profiles reveal parallel evolution of epistatic interactions involving the CRP regulon in Escherichia coli. PLoS Genet 4:e35.
- a systems-level approach to examine epistatic interactions that arose during the evolution of Escherichia coli in a defined environment
- we used expression arrays to compare the effect on global patterns of gene expression of deleting a central regulatory gene, crp
- effects were measured in two lineages that had independently evolved for 20,000 generations and in their common ancestor
- deleting crp had a much more dramatic effect on the expression profile of the two evolved lines than on the ancestor
- the sequence of the crp gene was unchanged during evolution
- these differences indicate epistatic interactions between crp and mutations at other loci that accumulated during evolution
- a striking degree of parallelism
- 115 genes that were not crp-dependent in the ancestor became dependent on crp in both evolved lines
- inference of epistatic interactions from fitness alone does not usually give any insight into their underlying genetic and physiological causes
