TY - JOUR TI - Single-molecule observation of ATP-independent SSB displacement by RecO in Deinococcus radiodurans AU - Hwang, Jihee AU - Kim, Jae-Yeol AU - Kim, Cheolhee AU - Park, Soojin AU - Joo, Sungmin AU - Kim, Seong Keun AU - Lee, Nam Ki A2 - Xiao, Jie A2 - Wolberger, Cynthia A2 - Robinson, Andrew VL - 9 PY - 2020 DA - 2020/04/16 SP - e50945 C1 - eLife 2020;9:e50945 DO - 10.7554/eLife.50945 UR - https://doi.org/10.7554/eLife.50945 AB - Deinococcus radiodurans (DR) survives in the presence of hundreds of double-stranded DNA (dsDNA) breaks by efficiently repairing such breaks. RecO, a protein that is essential for the extreme radioresistance of DR, is one of the major recombination mediator proteins in the RecA-loading process in the RecFOR pathway. However, how RecO participates in the RecA-loading process is still unclear. In this work, we investigated the function of drRecO using single-molecule techniques. We found that drRecO competes with the ssDNA-binding protein (drSSB) for binding to the freely exposed ssDNA, and efficiently displaces drSSB from ssDNA without consuming ATP. drRecO replaces drSSB and dissociates it completely from ssDNA even though drSSB binds to ssDNA approximately 300 times more strongly than drRecO does. We suggest that drRecO facilitates the loading of RecA onto drSSB-coated ssDNA by utilizing a small drSSB-free space on ssDNA that is generated by the fast diffusion of drSSB on ssDNA. KW - Deinococcus radiodurans KW - single-molecule spectroscopy KW - RecFOR pathway KW - SSB displacement KW - real-time observation KW - homologous recombination JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -