Refactoring the Genetic Code for Increased Evolvability
Gur Pines a,b, James D. Winkler a,b*, Assaf Pines, Ryan T. Gilla, b
a Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado, USA
b Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado, USA
Sang Yup Lee, Editor
- Author Affiliations
Korea Advanced Institute of Science and Technology
+ Author Notes
↵* Present address: James D. Winkler, Shell Biodomain, Houston, Texas, USA.
Address correspondence to Gur Pines, gur.pines@colorado.edu.
G.P. and J.D.W. contributed equally to this work.
ABSTRACT
The standard genetic code is robust to mutations during transcription and translation. Point mutations are likely to be synonymous or to preserve the chemical properties of the original amino acid. Saturation mutagenesis experiments suggest that in some cases the best-performing mutant requires replacement of more than a single nucleotide within a codon. These replacements are essentially inaccessible to common error-based laboratory engineering techniques that alter a single nucleotide per mutation event, due to the extreme rarity of adjacent mutations. In this theoretical study, we suggest a radical reordering of the genetic code that maximizes the mutagenic potential of single nucleotide replacements. We explore several possible genetic codes that allow a greater degree of accessibility to the mutational landscape and may result in a hyperevolvable organism that could serve as an ideal platform for directed evolution experiments. We then conclude by evaluating the challenges of constructing such recoded organisms and their potential applications within the field of synthetic biology.
IMPORTANCE
The conservative nature of the genetic code prevents bioengineers from efficiently accessing the full mutational landscape of a gene via common error-prone methods. Here, we present two computational approaches to generate alternative genetic codes with increased accessibility. These new codes allow mutational transitions to a larger pool of amino acids and with a greater extent of chemical differences, based on a single nucleotide replacement within the codon, thus increasing evolvability both at the single-gene and at the genome levels. Given the widespread use of these techniques for strain and protein improvement, along with more fundamental evolutionary biology questions, the use of recoded organisms that maximize evolvability should significantly improve the efficiency of directed evolution, library generation, and fitness maximization.
KEYWORDS evolution genetic code genome synthesis saturation mutagenesis
FOOTNOTES
Citation Pines G, Winkler JD, Pines A, Gill RT. 2017. Refactoring the genetic code for increased evolvability. mBio 8:e01654-17.
Received 7 September 2017 Accepted 10 October 2017 Published 14 November 2017
Copyright © 2017 Pines et al.
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
FREE PDF GRATIS: mBio
