Mutations in Global Regulators Lead to Metabolic Selection during Adaptation to Complex Environments

• DOI: 10.1371/journal.pgen.1004872
• Publication Date: 2014-12-11T19:04:24Z
• Authors: Gerda Saxer; Michael D. Krepps; Eric D. Merkley; Charles Ansong; Brooke L. Deather...; Marie-Thérèse Val...; Nikola Ristic; Ping T. Yeh; Vittal P. Prakash; Owen P. Leiser; Luay Nakhleh; Henry S. Gibbons; Helen W. Kreuzer; Yousif Shamoo
• Keywords: rpoS; Experimental Evolution; Epistasis; Genetic Fitness

Adaptation to ecologically complex environments can provide insights into the evolutionary dynamics and functional constraints encountered by organisms during natural selection. a new environment with abundant varied resources be difficult achieve small incremental changes if many mutations are required even modest gains in fitness. Since changing quite common nature, we investigated how such an epistatic bottleneck avoided allow rapid adaptation. We show that adaptive arise repeatedly independently evolved populations context of greatly increased genetic phenotypic diversity. go on weak selection requiring substantial metabolic reprogramming readily achieved global response regulator arcA stress rpoS. identified 46 unique single-nucleotide variants 18 rpoS, nine which resulted stop codons or large deletions, suggesting subtle modulations ArcA function knockouts rpoS largely responsible for shifts leading These higher order eliminates bottlenecks, could occur when would required. Proteomic carbohydrate analysis adapting E. coli revealed up-regulation enzymes associated TCA cycle amino acid metabolism, increase secretion putrescine. The overall effect adaptation across is redirect efficiently utilize uptake catabolism acids. Concomitantly, there pronounced spread more limited strains results from specialization through erosion. Remarkably, regulators "one-step" mechanism novel environment, highlights importance resource management as powerful strategy