The ecological consequences and evolution of retron-mediated suicide as a way to protect Escherichia coli from being killed by phage

• Type of Material: Article
• Authors: Brandon A Berryhill, Emory University; Joshua A Manuel, Emory University; Rodrigo Garcia, Emory University; Bruce Levin, Emory University
• Language: English
• Date: 2023-05-01
• Publisher: PLoS ONE
• Publication Version: Final Published Version
• Copyright Statement: © 2023 Berryhill et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0285274
• Title of Journal or Parent Work: PLoS ONE
• Volume: 18
• Issue: 5 MAY
• Start Page: e0285274
• End Page: e0285274
• Grant/Funding Information: Funds for this research were provided by a grant from the US National Institutes of General Medical Sciences (https://www.nigms.nih.gov/), R35GM136407 (BRL). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
• Keywords: RNA-Directed DNA Polymerase; Bacteriophages; DNA, Single-Stranded; DNA, Bacterial; Escherichia coli; Humans; DNA; Base Sequence

Abstract

Retrons were described in 1984 as DNA sequences that code for a reverse transcriptase and a unique single-stranded DNA/RNA hybrid called multicopy single-stranded DNA (msDNA). It would not be until 2020 that a function was shown for retrons, when compelling evidence was presented that retrons activate an abortive infection pathway in response to bacteriophage (phage) infection. When infected with the virulent mutant of the phage lambda, λVIR, and to a lesser extent, other phages, a retron designated Ec48 is activated, the Escherichia coli bearing this retron element dies, and the infecting phage is lost. With the aid of a mathematical model, we explore the a priori conditions under which retrons will protect bacterial populations from predation by phage and the conditions under which retron-bearing bacteria will evolve in populations without this element. Using isogenic E. coli with and without Ec48 and λVIR, we estimated the parameters of our model and tested the hypotheses generated from our analysis of its properties. Our models and experiments demonstrate that cells expressing a retron-mediated abortive infection system can protect bacterial populations. Our results demonstrate that retron bearing bacteria only have a competitive advantage under a limited set of conditions.