A superfamily 1 helicase translocates on double-stranded DNA
- 1Boston Children's Hospital
Abstract
Replicative and accessory helicases are essential for maintaining genome integrity during DNA replication and repair. Rep helicase belongs to superfamily 1 (SF1), the first helicase family solved at atomic resolution and a longstanding model for how helicases couple ATP hydrolysis to movement on DNA. Using optical tweezers combined with fluorescence imaging, we characterize how Rep translocates and navigates diverse nucleic acid and protein obstacles. We directly observe highly processive translocation on ssDNA (~300 nt/s over >13,000 nt) and show that this directional movement can drive single-stranded DNA-binding proteins (bacterial SSB, archaeal SSB, and eukaryotic RPA) along ssDNA without slowing. On encountering a short duplex barrier ([≤]60 bp), either a DNA duplex or an RNA/DNA hybrid, Rep frequently bypasses it, with termination and unwinding also observed. Unexpectedly, we identify a mode in which Rep transitions from ssDNA onto dsDNA and translocates directionally along the duplex with high processivity(>12,000bp) and at a much higher speed than on ssDNA (~1100 bp/s). AlphaFold3 modeling is consistent with Rep tracking a single strand while keeping the duplex intact. To our knowledge, this is the first demonstration of processive dsDNA translocation by an SF1 helicase, and it broadens models for how translocases operate on DNA during replication and repair.
Related
- RNA self-association limits the removal of double-stranded RNA by affinity chromatography
- Enhancing double-duplex invasion by using multiple parallel-stranded peptide nucleic acids
- AI-driven structural informatics reveals diverse glycosylation machinery across double-stranded DNA viruses
- Identification of cellular double-stranded RNAs in mammalian embryonic stem cells
- Double-Stranded RNA Profiling with Mass Photometry
BibTeX
@misc{pangeni2026superfamily,
title = {{A superfamily 1 helicase translocates on double-stranded DNA}},
author = {S. Pangeni and A. M. Nakara and O. Yang and F. Rashid and J. M. Berger and T. Ha},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.16.752024},
url = {https://www.biorxiv.org/content/10.64898/2026.09.16.752024v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - A superfamily 1 helicase translocates on double-stranded DNA
AU - S. Pangeni
AU - A. M. Nakara
AU - O. Yang
AU - F. Rashid
AU - J. M. Berger
AU - T. Ha
PY - 2026
DA - 2026/09/16
PB - bioRxiv
DO - 10.64898/2026.09.16.752024
UR - https://www.biorxiv.org/content/10.64898/2026.09.16.752024v1
AB - Replicative and accessory helicases are essential for maintaining genome integrity during DNA replication and repair. Rep helicase belongs to superfamily 1 (SF1), the first helicase family solved at atomic resolution and a longstanding model for how helicases couple ATP hydrolysis to movement on DNA. Using optical tweezers combined with fluorescence imaging, we characterize how Rep translocates and navigates diverse nucleic acid and protein obstacles. We directly observe highly processive translocation on ssDNA (~300 nt/s over >13,000 nt) and show that this directional movement can drive single-stranded DNA-binding proteins (bacterial SSB, archaeal SSB, and eukaryotic RPA) along ssDNA without slowing. On encountering a short duplex barrier ([≤]60 bp), either a DNA duplex or an RNA/DNA hybrid, Rep frequently bypasses it, with termination and unwinding also observed. Unexpectedly, we identify a mode in which Rep transitions from ssDNA onto dsDNA and translocates directionally along the duplex with high processivity(>12,000bp) and at a much higher speed than on ssDNA (~1100 bp/s). AlphaFold3 modeling is consistent with Rep tracking a single strand while keeping the duplex intact. To our knowledge, this is the first demonstration of processive dsDNA translocation by an SF1 helicase, and it broadens models for how translocases operate on DNA during replication and repair.
ER -