The phosphorylated trimeric SOSS1 complex and RNA polymerase II trigger liquid-liquid phase separation at double-strand breaks
Qilin Long,
Marek Sebesta,
Katerina Sedova,
Vojtech Haluza,
Adele Alagia,
Zhichao Liu,
Richard Stefl,
Monika Gullerova
Affiliations
Qilin Long
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
Marek Sebesta
Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic; Corresponding author
Katerina Sedova
Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic
Vojtech Haluza
Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic
Adele Alagia
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
Zhichao Liu
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
Richard Stefl
Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic; National Center for Biomolecular Research, Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
Monika Gullerova
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK; Corresponding author
Summary: Double-strand breaks (DSBs) are the most severe type of DNA damage. Previously, we demonstrated that RNA polymerase II (RNAPII) phosphorylated at the tyrosine 1 (Y1P) residue of its C-terminal domain (CTD) generates RNAs at DSBs. However, the regulation of transcription at DSBs remains enigmatic. Here, we show that the damage-activated tyrosine kinase c-Abl phosphorylates hSSB1, enabling its interaction with Y1P RNAPII at DSBs. Furthermore, the trimeric SOSS1 complex, consisting of hSSB1, INTS3, and c9orf80, binds to Y1P RNAPII in response to DNA damage in an R-loop-dependent manner. Specifically, hSSB1, as a part of the trimeric SOSS1 complex, exhibits a strong affinity for R-loops, even in the presence of replication protein A (RPA). Our in vitro and in vivo data reveal that the SOSS1 complex and RNAPII form dynamic liquid-like repair compartments at DSBs. Depletion of the SOSS1 complex impairs DNA repair, underscoring its biological role in the R-loop-dependent DNA damage response.
