Redox-dependent condensation and cytoplasmic granulation by human ssDNA-binding protein-1 delineate roles in oxidative stress response
Gábor M. Harami,
János Pálinkás,
Zoltán J. Kovács,
Bálint Jezsó,
Krisztián Tárnok,
Hajnalka Harami-Papp,
József Hegedüs,
Lamiya Mahmudova,
Nóra Kucsma,
Szilárd Tóth,
Gergely Szakács,
Mihály Kovács
Affiliations
Gábor M. Harami
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
János Pálinkás
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Zoltán J. Kovács
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary; HUN-REN-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Bálint Jezsó
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Krisztián Tárnok
Department of Physiology and Neurobiology, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Hajnalka Harami-Papp
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
József Hegedüs
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Lamiya Mahmudova
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary
Nóra Kucsma
HUN-REN Institute of Molecular Life Sciences, Research Centre for Natural Sciences, Magyar Tudósok körútja 2, 1117 Budapest, Hungary
Szilárd Tóth
HUN-REN Institute of Molecular Life Sciences, Research Centre for Natural Sciences, Magyar Tudósok körútja 2, 1117 Budapest, Hungary
Gergely Szakács
HUN-REN Institute of Molecular Life Sciences, Research Centre for Natural Sciences, Magyar Tudósok körútja 2, 1117 Budapest, Hungary; Center for Cancer Research, Medical University of Vienna, Borschkegasse 8a, 1090 Wien, Austria
Mihály Kovács
ELTE-MTA “Momentum” Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary; HUN-REN-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, 1117 Budapest, Hungary; Corresponding author
Summary: Human single-stranded DNA binding protein 1 (hSSB1/NABP2/OBFC2B) plays central roles in DNA repair. Here, we show that purified hSSB1 undergoes redox-dependent liquid-liquid phase separation (LLPS) in the presence of single-stranded DNA or RNA, features that are distinct from those of LLPS by bacterial SSB. hSSB1 nucleoprotein droplets form under physiological ionic conditions in response to treatment modeling cellular oxidative stress. hSSB1’s intrinsically disordered region is indispensable for LLPS, whereas all three cysteine residues of the oligonucleotide/oligosaccharide-binding fold are necessary to maintain redox-sensitive droplet formation. Proteins interacting with hSSB1 show selective enrichment inside hSSB1 droplets, suggesting tight content control and recruitment functions for the condensates. While these features appear instrumental for genome repair, we detected cytoplasmic hSSB1 condensates in various cell lines colocalizing with stress granules upon oxidative stress, implying extranuclear function in cellular stress response. Our results suggest condensation-linked roles for hSSB1, linking genome repair and cytoplasmic defense.
