Proceedings of the National Academy of Sciences· 2026Q1
Two D-loop resolution systems enable natural genetic transformation in bacteria
- 4citations
- Q1SCImago
- 2026year
Short summary
Bacteria utilize two distinct endonuclease/helicase pairs, YraN/ComM and CoiA/RadA, to resolve the D-loop intermediate during natural genetic transformation, enabling the integration of extracellular DNA into their genomes.
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Key points
- Natural transformation in bacteria involves integrating extracellular DNA into the genome via homologous recombination, proceeding through a RecA-directed D-loop intermediate.
- Two endonucleases, YraN and CoiA, have been identified as crucial for resolving the transformation D-loop.
- YraN interacts with the ComM helicase and is widely distributed in bacteria.
- CoiA, restricted to Bacillota, acts as a resolvase and functions with the RadA helicase.
- Both YraN/ComM and CoiA/RadA systems work synergistically, indicating two distinct evolutionary pathways for D-loop resolution.
AI-generated from the title and abstract; the full text is not read.
Abstract
Natural transformation is a widespread mechanism driving genetic exchanges in bacteria. It proceeds from the capture of extracellular DNA released by other cells. Internalized in linear single strands, this exogenous DNA is ultimately integrated into the genome by homologous recombination. It is unknown how the RecA-directed D-loop intermediate of this dedicated recombination pathway is processed. We report that resolution of the transformation D-loop depends on two endonucleases of opposing phylogenetic distribution in bacteria. One is YraN, which has coevolved and interacts with the ComM helicase, known to extend DNA recombination at the transformation D-loop. The other is CoiA, which is restricted to the Bacillota. CoiA is shown to be a resolvase of the transformation D-loop, extended by the RadA helicase in these species. We demonstrate that both YraN and CoiA act synergistically with their cognate helicases. These findings reveal that bacteria have evolved two helicase/nuclease pairs for the maturation and recombination extension of the transformation D-loop. The wide distribution of this dual system indicates that recombination of exogenous DNA by natural transformation is an ancestral and pervasive feature of bacteria.
The authors' abstract, as published at the source. Proceedings of the National Academy of Sciences, 2026 · DOI ↗
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Field: Genetics (Biochemistry, Genetics and Molecular Biology)
GeneticsBiochemistry, Genetics and Molecular Biology