Oligo- and dsDNA-mediated genome editing using a tetA dual selection system in Escherichia coli

PLoS One. 2017 Jul 18;12(7):e0181501. doi: 10.1371/journal.pone.0181501. eCollection 2017.

Abstract

The ability to precisely and seamlessly modify a target genome is needed for metabolic engineering and synthetic biology techniques aimed at creating potent biosystems. Herein, we report on a promising method in Escherichia coli that relies on the insertion of an optimized tetA dual selection cassette followed by replacement of the same cassette with short, single-stranded DNA (oligos) or long, double-stranded DNA and the isolation of recombinant strains by negative selection using NiCl2. This method could be rapidly and successfully used for genome engineering, including deletions, insertions, replacements, and point mutations, without inactivation of the methyl-directed mismatch repair (MMR) system and plasmid cloning. The method we describe here facilitates positive genome-edited recombinants with selection efficiencies ranging from 57 to 92%. Using our method, we increased lycopene production (3.4-fold) by replacing the ribosome binding site (RBS) of the rate-limiting gene (dxs) in the 1-deoxy-D-xylulose-5-phosphate (DXP) biosynthesis pathway with a strong RBS. Thus, this method could be used to achieve scarless, proficient, and targeted genome editing for engineering E. coli strains.

MeSH terms

  • Antiporters / metabolism*
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Chromosomes, Bacterial / genetics
  • DNA, Single-Stranded / genetics*
  • Escherichia coli / genetics*
  • Gene Editing / methods*
  • Genomics*
  • Metabolic Engineering
  • Pentosephosphates / biosynthesis

Substances

  • 1-deoxylulose 5-phosphate
  • Antiporters
  • Bacterial Proteins
  • DNA, Single-Stranded
  • Pentosephosphates
  • tetA protein, Bacteria

Grants and funding

This work was supported by the National Research Foundation of Korea (NRF) through grants funded by the Ministry of Education (2013R1A1A2058667) and by a grant from the Next-Generation Bio Green 21 Program (SSAC, PJ011181), Rural Development Administration, Republic of Korea. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.