Organisms with alternative genetic codes resolve unassigned codons via mistranslation and ribosomal rescue
Abstract
Organisms possessing genetic codes with unassigned codons raise the question of how cellular machinery resolves such codons and how this could impact horizontal gene transfer. Here, we use a genomically recoded Escherichia coli to examine how organisms address translation at unassigned UAG codons, which obstruct propagation of UAG-containing viruses and plasmids. Using mass spectrometry, we show that recoded organisms resolve translation at unassigned UAG codons via near-cognate suppression, dramatic frameshifting from at least −3 to +19 nucleotides, and rescue by ssrA-encoded tmRNA, ArfA, and ArfB. We then demonstrate that deleting tmRNA restores expression of UAG-ending proteins and propagation of UAG-containing viruses and plasmids in the recoded strain, indicating that tmRNA rescue and nascent peptide degradation is the cause of impaired virus and plasmid propagation. The ubiquity of tmRNA homologs suggests that genomic recoding is a promising path for impairing horizontal gene transfer and conferring genetic isolation in diverse organisms.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 30, 2018
- Source ID
- 10.7554/elife.34878
Entities
People
- Colin Hemez
- Farren J Isaacs
- Jesse Rinehart
- Karl W Barber
- Natalie J Ma
Organizations
- Arnold and Mabel Beckman Foundation
- Defense Advanced Research Projects Agency
- DuPont
- Gruber Foundation
- National Institutes of Health
- National Science Foundation
- United States Department of Energy
- Yale University