Unbiased homeologous recombination during pneumococcal transformation allows for multiple chromosomal integration events
Abstract
The spread of antimicrobial resistance and vaccine escape in the human pathogen Streptococcus pneumoniae can be largely attributed to competence-induced transformation. Here, we studied this process at the single-cell level. We show that within isogenic populations, all cells become naturally competent and bind exogenous DNA. We find that transformation is highly efficient and that the chromosomal location of the integration site or whether the transformed gene is encoded on the leading or lagging strand has limited influence on recombination efficiency. Indeed, we have observed multiple recombination events in single recipients in real-time. However, because of saturation and because a single stranded donor DNA replaces the original allele, transformation efficiency has an upper threshold of approximately 50% of the population. The fixed mechanism of transformation results in a fail-safe strategy for the population as half of the population generally keeps an intact copy of the original genome.
Data availability
This work is mainly based upon microscopy and snap shots and movies of most experiments are included in the manuscript and supporting files. Raw microscopy images will be made available at the BioImages Archive (accession S-BIAD26).
Article and author information
Author details
Funding
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (31003A_172861)
- Jan-Willem Veening
European Commission (771534- PneumoCaTChER.)
- Jan-Willem Veening
Agence Nationale de la Recherche (ANR-10-BLAN-1331)
- Patrice Polard
Naito Foundation
- Jun Kurushima
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (40AR40_185533)
- Jan-Willem Veening
Agence Nationale de la Recherche (EXStasis-17-CE13-0031-01)
- Patrice Polard
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Petra Anne Levin, Washington University in St. Louis, United States
Version history
- Received: May 11, 2020
- Accepted: September 22, 2020
- Accepted Manuscript published: September 23, 2020 (version 1)
- Version of Record published: October 16, 2020 (version 2)
Copyright
© 2020, Kurushima et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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