Biophysical foundations of evolutionary dynamics

The overarching goal of this research is to develop predictive multiscale biophysical models of adaptive evolutionary dynamics. The new concept of Biophysical Fitness Landscape (BFL) is a map of protein/nucleic acid molecular properties to fitness. We demonstrated the conceptual validity of BFL by discovering a simple and accurate quantitative relationship between fitness of E. coli and molecular properties of important core metabolic enzymes. This finding transforms the concept of fitness landscape from an artful metaphor into a quantitative tractable tool to predict the genotype-phenotype relationship (GPR). Here we take these findings as a foundation to further extend our understanding of interplay between biophysical and population factors that determine the dynamics and outcome of adaptive evolution. We will apply biophysical analysis, automated robotics setup along with protein engineering and genomic editing tools to explore evolutionary dynamics in laboratory experiments under conditions that allow tight control on all scales – from molecules to populations. As a key model we carry out a set of evolution experiments with adapting populations of E. coli escaping from antibiotic stress and structural instability of the essential protein Dihydrofolate Reductase. We characterize on all scales – genotyping, molecular traits, systems proteomics and metabolomics and population - multiple evolutionary paths to resistance and adaption of emerging bacterial strains and determine at which level of description (genotype, biophysical properties, systems responses) evolution becomes reproducible – and by implication predictable. We model the evolutionary dynamics using multiscale models where cytoplasm of model cells is presented in a biophysically realistic manner, and fitness of model organisms is predicted from its molecular traits using experimentally derived BFL. Comprehensive molecular mapping of possible escape routes will provide an opportunity to rationally design new class of compounds – “evolution drugs” - that comprehensively block pathogen’s resistance. In a related effort we will explore the biophysical underpinnings of codon adaptation to discern their effects on mRNA and cotranslational protein folding. A tight integration between theory and experiment will provide an opportunity to develop predictive evolutionary models of ever increasing accuracy and realism. Progress along these lines will transform our approaches to study evolutionary dynamics from descriptive into predictive and quantitative, which will be instrumental to the development of novel approaches to fight antibiotic resistance and, potentially, viral escape from stressors such as drugs and immune response.