Single-Molecule Visualization of Human BLM Helicase as it Acts Upon Double- and Single-Stranded DNA Substrates

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dc.contributor.authorXue, Chaoyou
dc.contributor.authorDaley, James M.
dc.contributor.authorXue, Xiaoyu
dc.contributor.authorSteinfeld, Justin
dc.contributor.authorKwon, Youngho
dc.contributor.authorSung, Patrick
dc.contributor.authorGreene, Eric C.
dc.date.accessioned2020-03-11T13:37:17Z
dc.date.available2020-03-11T13:37:17Z
dc.date.issued2019-09
dc.description.abstractBloom helicase (BLM) and its orthologs are essential for the maintenance of genome integrity. BLM defects represent the underlying cause of Bloom Syndrome, a rare genetic disorder that is marked by strong cancer predisposition. BLM deficient cells accumulate extensive chromosomal aberrations stemming from dysfunctions in homologous recombination (HR). BLM participates in several HR stages and helps dismantle potentially harmful HR intermediates. However, much remains to be learned about the molecular mechanisms of these BLM-mediated regulatory effects. Here, we use DNA curtains to directly visualize the activity of BLM helicase on single molecules of DNA. Our data show that BLM is a robust helicase capable of rapidly (∼70-80 base pairs per second) unwinding extensive tracts (∼8-10 kilobases) of double-stranded DNA (dsDNA). Importantly, we find no evidence for BLM activity on single-stranded DNA (ssDNA) that is bound by replication protein A (RPA). Likewise, our results show that BLM can neither associate with nor translocate on ssDNA that is bound by the recombinase protein RAD51. Moreover, our data reveal that the presence of RAD51 also blocks BLM translocation on dsDNA substrates. We discuss our findings within the context of potential regulator roles for BLM helicase during DNA replication and repair.
dc.description.departmentChemistry and Biochemistry
dc.formatText
dc.format.extent13 pages
dc.format.medium1 file (.pdf)
dc.identifier.citationXue, C., Daley, J. M., Xue, X., Steinfeld, J., Kwon, Y., Sung, P., & Greene, E. C. (2019). Single-molecule visualization of human BLM helicase as it acts upon double- and single-stranded DNA substrates. Nucleic Acids Research, 47(21), pp. 11225–11237.
dc.identifier.doihttps://doi.org/10.1093/nar/gkz810
dc.identifier.issn1362-4962
dc.identifier.urihttps://hdl.handle.net/10877/9372
dc.language.isoen
dc.publisherOxford University Press
dc.rights.licenseThis work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
dc.sourceNucleic Acids Research, 2019, Vol. 47, No. 21, pp. 11225–11237.
dc.subjectbloom helicase
dc.subjectBLM
dc.subjectgenome integrity
dc.subjecthomologous recombination
dc.subjectChemistry and Biochemistry
dc.titleSingle-Molecule Visualization of Human BLM Helicase as it Acts Upon Double- and Single-Stranded DNA Substrates
dc.typeArticle

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