RNA/DNA hybrid binding affinity determines telomerase template- translocation efficiency

Xiaodong Qi, Mingyi Xie, Andrew F. Brown, Christopher J. Bley, Joshua D. Podlevsky, Julian Chen

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Telomerase synthesizes telomeric DNA repeats onto chromosome termini from an intrinsic RNA template. The processive synthesis of DNA repeats relies on a unique, yet poorly understood, mechanism whereby the telomerase RNA template translocates and realigns with the DNA primer after synthesizing each repeat. Here, we provide evidence that binding of the realigned RNA/DNA hybrid by the active site is an essential step for template translocation. Employing a template-free human telomerase system, we demonstrate that the telomerase active site directly binds to RNA/DNA hybrid substrates for DNA polymerization. In telomerase processivity mutants, the template-translocation efficiency correlates with the affinity for the RNA/DNA hybrid substrate. Furthermore, the active site is unoccupied during template translocation as a 5 bp extrinsic RNA/DNA hybrid effectively reduces the processivity of the template-containing telomerase. This suggests that strand separation and template realignment occur outside the active site, preceding the binding of realigned hybrid to the active site. Our results provide new insights into the ancient RNA/DNA hybrid binding ability of telomerase and its role in template translocation.

Original languageEnglish (US)
Pages (from-to)150-161
Number of pages12
JournalEMBO Journal
Volume31
Issue number1
DOIs
StatePublished - Jan 4 2012

Keywords

  • processivity
  • reverse transcriptase
  • telomere
  • template translocation

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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