Girasol, M. J. et al. (2023) RAD51-mediated R-loop formation acts to repair transcription associated DNA breaks driving antigenic variation in Trypanosoma brucei. Proceedings of the National Academy of Sciences of the United States of America, 120(48), e230930612. (doi: 10.1073/pnas.2309306120) (PMID:37988471) (PMCID:PMC10691351)
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Abstract
RNA–DNA hybrids are epigenetic features of all genomes that intersect with many processes, including transcription, telomere homeostasis, and centromere function. Increasing evidence suggests that RNA–DNA hybrids can provide two conflicting roles in the maintenance and transmission of genomes: They can be the triggers of DNA damage, leading to genome change, or can aid the DNA repair processes needed to respond to DNA lesions. Evasion of host immunity by African trypanosomes, such as Trypanosoma brucei, relies on targeted recombination of silent Variant Surface Glycoprotein (VSG) genes into a specialized telomeric locus that directs transcription of just one VSG from thousands. How such VSG recombination is targeted and initiated is unclear. Here, we show that a key enzyme of T. brucei homologous recombination, RAD51, interacts with RNA–DNA hybrids. In addition, we show that RNA–DNA hybrids display a genome-wide colocalization with DNA breaks and that this relationship is impaired by mutation of RAD51. Finally, we show that RAD51 acts to repair highly abundant, localised DNA breaks at the single transcribed VSG and that mutation of RAD51 alters RNA–DNA hybrid abundance at 70 bp repeats both around the transcribed VSG and across the silent VSG archive. This work reveals a widespread, generalised role for RNA–DNA hybrids in directing RAD51 activity during recombination and uncovers a specialised application of this interplay during targeted DNA break repair needed for the critical T. brucei immune evasion reaction of antigenic variation.
| Item Type: | Articles |
|---|---|
| Additional Information: | This work was funded by the Philippine Council for Health Research and Development (M.J.G.), a Wellcome Trust Investigator Award (224501/Z/21/Z, R.M.), a Henry Wellcome fellowship (218648/Z/19/Z, E.M.B.), an Institutional Strategic Support Fund award to the University of Glasgow (204820/Z/16/Z), and by the BBSRC (BB/N016165/1 and BB/R017166/1, BB/W001101/1, C.A.M. and R.M.). The Wellcome Centre for Integrative Parasitology is funded by a Wellcome Trust Strategic Award (104111/Z/14/Z/A). |
| Keywords: | trypanosome, antigenic variation, RNA-DNA hybrid, DNA repair, recombination. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Burchmore, Dr Richard and Briggs, Miss Emma and Lapsley, Mr Craig and McCulloch, Professor Richard and Beraldi, Dr Dario and Krasilnikova, Ms Marija and Damasceno, Dr Jeziel and Girasol, Mr Mark and Carruthers, Dr Ross and Lemgruber Soares, Dr Leandro |
| Authors: | Girasol, M. J., Krasilnikova, M., Marques, C. A., Damasceno, J. D., Lapsley, C., Lemgruber, L., Burchmore, R., Beraldi, D., Carruthers, R., Briggs, E. M., and McCulloch, R. |
| College/School: | College of Medical Veterinary and Life Sciences College of Medical Veterinary and Life Sciences > School of Cancer Sciences |
| Journal Name: | Proceedings of the National Academy of Sciences of the United States of America |
| Publisher: | National Academy of Sciences |
| ISSN: | 0027-8424 |
| ISSN (Online): | 1091-6490 |
| Published Online: | 21 November 2023 |
| Copyright Holders: | Copyright: © 2023 The Author(s) |
| First Published: | First published in Proceedings of the National Academy of Sciences of the United States of America 120(48): e2309306120 |
| Publisher Policy: | Reproduced under a Creative Commons licence |
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