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bioRxiv · 10.1101/313338

Scalable continuous evolution of genes at mutation rates above genomic error thresholds

Ravikumar, A.·Arzumanyan, G. A.·Obadi, M. K. A.·Javanpour, A. A.·Liu, C. C.
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Abstract

Directed evolution is a powerful approach for engineering biomolecules and understanding adaptation1-3. However, experimental strategies for directed evolution are notoriously low-throughput, limiting access to demanding functions, multiple functions in parallel, and the study of molecular evolution in replicate. Here, we report OrthoRep, a yeast orthogonal DNA polymerase-plasmid pair that stably mutates ~100,000-fold faster than the host genome in vivo, exceeding error thresholds of genomic replication that lead to single-generation extinction4. User-defined genes in OrthoRep continuously and rapidly evolve through serial passaging, a highly scalable process. Using OrthoRep, we evolved drug resistant malarial DHFRs 90 times and uncovered a more complex fitness landscape than previously realized5-9. We find rare fitness peaks that resist the maximum soluble concentration of the antimalarial pyrimethamine - these resistant variants support growth at pyrimethamine concentrations >40,000-fold higher than the wild-type enzyme can tolerate - and also find that epistatic interactions direct adaptive trajectories to convergent outcomes. OrthoRep enables a new paradigm of routine, high-throughput evolution of biomolecular and cellular function.

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Ravikumar, A., Arzumanyan, G. A., Obadi, M. K. A., Javanpour, A. A., Liu, C. C.. 2018-05-03. Scalable continuous evolution of genes at mutation rates above genomic error thresholds. https://doi.org/10.1101/313338

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