The human RAD52 complex undergoes phase separation and facilitates bundling and end-to-end tethering of RAD51 presynaptic filaments

Ibraheem Alshareedah; Sushil Pangeni; Paul A Dewan Jr; Masayoshi Honda; Ting-Wei Liao; Maria Spies; Taekjip Ha

doi:10.1093/nar/gkag043

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The human RAD52 complex undergoes phase separation and facilitates bundling and end-to-end tethering of RAD51 presynaptic filaments

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The human RAD52 complex undergoes phase separation and facilitates bundling and end-to-end tethering of RAD51 presynaptic filaments

Ibraheem Alshareedah, Sushil Pangeni, Paul A Dewan Jr, Masayoshi Honda, Ting-Wei Liao, Maria Spies and Taekjip Ha

Nucleic acids research, Vol.54(3), gkag043

01/22/2026

DOI: 10.1093/nar/gkag043

PMID: 41603734

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Abstract

Human RAD52 is a prime target for synthetic lethality approaches to treat cancers with deficiency in homologous recombination. Among multiple cellular roles, RAD52's functions in homologous recombination repair and stalled replication fork protection appear to substitute for those of the tumor suppressor protein BRCA2. However, the mechanistic details of how RAD52 substitutes for BRCA2 functions are only beginning to emerge. RAD52 forms an oligomeric ring enveloped by ∼200-residue-long disordered regions, forming a highly multivalent and branched protein complex that promotes supramolecular assembly. Here, we demonstrate that RAD52 undergoes homotypic phase separation, forming condensates that recruit key homologous recombination factors, including single-stranded DNA (ssDNA), replication protein A (RPA), and the RAD51 recombinase. Furthermore, we show that RAD52 phase separation is regulated by its interaction partners such as ssDNA and RPA. Through fluorescence microscopy, we observe that RAD52 promotes the formation of RAD51-ssDNA fibrillar structures. To resolve the fine architecture of these fibrils, we employed single-molecule super-resolution imaging via DNA-PAINT and atomic force microscopy, revealing that RAD51 fibrils comprise bundles of individual RAD51 nucleoprotein filaments. Additionally, we show that RAD52 induces end-to-end tethering of RAD51 nucleoprotein filaments. Collectively, these findings highlight distinctive macromolecular organizational features of RAD52 that may underpin its diverse cellular functions.

BRCA2 Protein - genetics

DNA, Single-Stranded - genetics

DNA, Single-Stranded - metabolism

Homologous Recombination

Humans

Phase Separation

Protein Binding

Rad51 Recombinase - chemistry

Rad51 Recombinase - genetics

Rad51 Recombinase - metabolism

Rad52 DNA Repair and Recombination Protein - chemistry

Rad52 DNA Repair and Recombination Protein - genetics

Rad52 DNA Repair and Recombination Protein - metabolism

Replication Protein A - genetics

Replication Protein A - metabolism

Details

Title: Subtitle: The human RAD52 complex undergoes phase separation and facilitates bundling and end-to-end tethering of RAD51 presynaptic filaments
Creators: Ibraheem Alshareedah - Harvard University
Sushil Pangeni - Johns Hopkins University
Paul A Dewan Jr - Boston Children's Hospital
Masayoshi Honda - University of Iowa
Ting-Wei Liao - Johns Hopkins University
Maria Spies - University of Iowa
Taekjip Ha - Harvard University
Resource Type: Journal article
Publication Details: Nucleic acids research, Vol.54(3), gkag043
DOI: 10.1093/nar/gkag043
PMID: 41603734
NLM abbreviation: Nucleic Acids Res
ISSN: 0305-1048
eISSN: 1362-4962
Publisher: Oxford University Press
Grant note: NIGMS NIH HHS R01CA232425 / NCI NIH HHS R35 GM122569 / NIH HHS HHMI Jane Coffin Childs Memorial Fund
Language: English
Date published: 01/22/2026
Academic Unit: Radiation Oncology; Biochemistry and Molecular Biology
Record Identifier: 9985132080002771

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