Nanoscale Analysis of SSB–RecO Interplay in SSB Interaction with the Target
- 1Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
Abstract
Single-stranded DNA-binding protein (SSB) coats single-stranded DNA (ssDNA) and recruits downstream factors, yet this same coating must be cleared for SSB-interacting proteins to bind. RecA is a central protein in homologous recombination, which requires SSB-free ssDNA to load during the process. RecO, a recombination mediator protein, is thought to regulate this handoff, but it has not been shown directly that RecO drives the release of full-length, ssDNA-bound SSB. Using atomic force microscopy, we show that RecO actively displaces full-length wild-type SSB from a defined ssDNA substrate, reducing occupancy from 67% to 29%. Displacement efficiency decreases after deleting the C-terminal tip of SSB (ΔC8) or after adding a single alanine at the C-terminus of SSB (A179). Molecular dynamics simulations show that A179 retains its native RecO contact but additionally engages a non-native surface, producing a specific, over-engaged complex, suggesting that these interprotein interactions may affect SSB-ssDNA contacts. Together, these findings suggest that RecO-driven SSB clearance is governed by the protein–protein interface rather than by ssDNA-binding affinity alone, thereby acting as a checkpoint against indiscriminate SSB removal during genome maintenance.
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BibTeX
@article{irukuvajjula2026nanoscale,
title = {{Nanoscale Analysis of SSB–RecO Interplay in SSB Interaction with the Target}},
author = {Shivkumar Sharma Irukuvajjula and Shaun Filliaux and Yuri L. Lyubchenko},
journal = {International Journal of Molecular Sciences},
year = {2026},
month = oct,
doi = {10.3390/ijms27198858},
url = {https://www.mdpi.com/1422-0067/27/19/8858},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Nanoscale Analysis of SSB–RecO Interplay in SSB Interaction with the Target
AU - Shivkumar Sharma Irukuvajjula
AU - Shaun Filliaux
AU - Yuri L. Lyubchenko
PY - 2026
DA - 2026/10/04
JO - International Journal of Molecular Sciences
DO - 10.3390/ijms27198858
UR - https://www.mdpi.com/1422-0067/27/19/8858
AB - Single-stranded DNA-binding protein (SSB) coats single-stranded DNA (ssDNA) and recruits downstream factors, yet this same coating must be cleared for SSB-interacting proteins to bind. RecA is a central protein in homologous recombination, which requires SSB-free ssDNA to load during the process. RecO, a recombination mediator protein, is thought to regulate this handoff, but it has not been shown directly that RecO drives the release of full-length, ssDNA-bound SSB. Using atomic force microscopy, we show that RecO actively displaces full-length wild-type SSB from a defined ssDNA substrate, reducing occupancy from 67% to 29%. Displacement efficiency decreases after deleting the C-terminal tip of SSB (ΔC8) or after adding a single alanine at the C-terminus of SSB (A179). Molecular dynamics simulations show that A179 retains its native RecO contact but additionally engages a non-native surface, producing a specific, over-engaged complex, suggesting that these interprotein interactions may affect SSB-ssDNA contacts. Together, these findings suggest that RecO-driven SSB clearance is governed by the protein–protein interface rather than by ssDNA-binding affinity alone, thereby acting as a checkpoint against indiscriminate SSB removal during genome maintenance.
SN - 1422-0067
ER -