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A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution

Journal Article


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Abstract


  • © 2020, Paudel et al. Telomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.

Authors


  •   Paudel, Bishnu
  •   Moye, Aaron L. (external author)
  •   Abou Assi, Hala (external author)
  •   El-Khoury, Roberto (external author)
  •   Cohen, Scott (external author)
  •   Holien, Jessica (external author)
  •   Birrento, Monica L. (external author)
  •   Samosorn, Siritrin (external author)
  •   Intharapichai, Kamthorn (external author)
  •   Tomlinson, Christopher (external author)
  •   Teulade-Fichou, Marie (external author)
  •   González, Carlos (external author)
  •   Beck, Jennifer L.
  •   Damha, Masad (external author)
  •   van Oijen, Antoine M.
  •   Bryan, Tracy (external author)

Publication Date


  • 2020

Published In


Citation


  • Paudel, B., Moye, A., Abou Assi, H., El-Khoury, R., Cohen, S., Holien, J., Birrento, M., Samosorn, S., Intharapichai, K., Tomlinson, C., Teulade-Fichou, M., González, C., Beck, J. L., Damha, M., van Oijen, A. & Bryan, T. (2020). A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution. eLife, 9 e56428.

Scopus Eid


  • 2-s2.0-85089610831

Ro Full-text Url


  • https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2556&context=smhpapers1

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/1522

Start Page


  • e56428

Volume


  • 9

Place Of Publication


  • United Kingdom

Abstract


  • © 2020, Paudel et al. Telomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.

Authors


  •   Paudel, Bishnu
  •   Moye, Aaron L. (external author)
  •   Abou Assi, Hala (external author)
  •   El-Khoury, Roberto (external author)
  •   Cohen, Scott (external author)
  •   Holien, Jessica (external author)
  •   Birrento, Monica L. (external author)
  •   Samosorn, Siritrin (external author)
  •   Intharapichai, Kamthorn (external author)
  •   Tomlinson, Christopher (external author)
  •   Teulade-Fichou, Marie (external author)
  •   González, Carlos (external author)
  •   Beck, Jennifer L.
  •   Damha, Masad (external author)
  •   van Oijen, Antoine M.
  •   Bryan, Tracy (external author)

Publication Date


  • 2020

Published In


Citation


  • Paudel, B., Moye, A., Abou Assi, H., El-Khoury, R., Cohen, S., Holien, J., Birrento, M., Samosorn, S., Intharapichai, K., Tomlinson, C., Teulade-Fichou, M., González, C., Beck, J. L., Damha, M., van Oijen, A. & Bryan, T. (2020). A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution. eLife, 9 e56428.

Scopus Eid


  • 2-s2.0-85089610831

Ro Full-text Url


  • https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2556&context=smhpapers1

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/1522

Start Page


  • e56428

Volume


  • 9

Place Of Publication


  • United Kingdom