Werner syndrome protein works as a dimer for unwinding and replication fork regression |
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| Authors: | Soochul Shin,Kwangbeom Hyun,Jinwoo Lee,Dongwon Joo,Tomasz Kulikowicz,Vilhelm A Bohr,Jaehoon Kim,Sungchul Hohng |
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| Affiliation: | Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea;Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea;Section on DNA repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA |
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| Abstract: | The determination of the oligomeric state of functional enzymes is essential for the mechanistic understanding of their catalytic activities. RecQ helicases have diverse biochemical activities, but it is still unclear how their activities are related to their oligomeric states. We use single-molecule multi-color fluorescence imaging to determine the oligomeric states of Werner syndrome protein (WRN) during its unwinding and replication fork regression activities. We reveal that WRN binds to a forked DNA as a dimer, and unwinds it without any change of its oligomeric state. In contrast, WRN binds to a replication fork as a tetramer, and is dimerized during activation of replication fork regression. By selectively inhibiting the helicase activity of WRN on specific strands, we reveal how the active dimers of WRN distinctly use the energy of ATP hydrolysis for repetitive unwinding and replication fork regression. |
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