LifeB | Laboratory of interaction and function of essential biomolecules

Publications

Quantitative Biology of Human Shelterin and Telomerase: Searching for the Weakest Point

In this review, we summarize quantitative assessments and structural information describing human shelterin and telomerase along with the status of the most promising approaches to telomerase inhibition in cancer cells. We focus on how shelterin allows telomerase action. We evaluate how the identified critical interactions of telomerase and shelterin might be elucidated in future research of new anticancer strategies.

We review:

  • Shelterin structure and binding features
  • Telomerase structure and function
  • Telomerase recruitment via shelterin
  • Quantitative description of interactions within shelterin
  • Implications for anticancer drug design

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Human Telomere Repeat Binding Factor TRF1 Replaces TRF2 Bound to Shelterin Core Hub TIN2 when TPP1 Is Absent

We showed that telomeric repeat binding factor TRF1 can replace TRF2 on TIN2. We described the role of TPP1 as a mediator of the shelterin core assembly at the single-molecule level.

Highlights:

  • TRF1 induces release of TRF2 from TIN2
  • TPP1 causes changes of TIN2, so TIN2–TPP1 complex can accommodate both TRF1 and TRF2
  • A model that explains TPP1 requirement for simultaneous binding of TRF1 and TRF2 to TIN2 is presented

We propose a molecular mechanism that interprets why TPP1 is essential for the stable formation of TRF1–TIN2–TRF2 core shelterin complex.

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Basic domain of telomere guardian TRF2 reduces D-loop unwinding whereas RAP1 restores it

We explain how telomeric proteins TRF2 and RAP1 modify BLM helicase activity and processing of displacement loop (D-loop) during replication of telomeres.  We addressed the role of the basic domain (B-domain) of TRF2 in the stabilization of DNA loops.

Highlights:

  • The B-domain of TRF2 stabilizes of the D-loop and diminishes DNA unwinding
  • The B- domain upon binding to DNA forms a rigid complex
  • Rap1 complexation with TRF2 restores D-loop susceptibility to unwinding

We suggested a mechanism for how the B-domain stabilizes D-loop and how RAP1 reverts the stabilization.




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Human Rap1 modulates TRF2 attraction to telomeric DNA

Our quantitative functional studies explain how telomeric proteins cooperate in order to selectively recognize human telomeric DNA. We investigated human Rap1–TRF2–DNA interactions by quantitative approaches. Our findings could be applied on all proteins that recognize DNA selectively and preserve genome stability.

Highlights:

  • Rap1 reduces DNA duplex binding of TRF2
  • Rap1 improves TRF2 selectivity for telomeric DNA
    by reduction of non-specific electrostatic interactions
  • Rap1 induces a partial release of TRF2 from telomeric DNA duplex

We suggested a possible mechanism of how Rap1 affects the recognition of telomeric DNA by TRF2

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Contributions of the TEL-patch Amino Acid Cluster on TPP1 to Telomeric DNA Synthesis by Human Telomerase

These quantitative observations describe how the TEL-patch part of telomeric protein TPP1 stabilizes telomerase on telomeric DNA and explains its contributions to telomerase recruitment and action.

Highlights:

  • The TEL-patch on TPP1 promotes telomerase translocation
  • The TEL-patch of TPP1 reduces telomerase dissociation from DNA
  • We developed an in vitro assay for telomerase recruitment to DNA
  • Telomerase interacts with TPP1 to preferentially bind and extend telomeric DNA


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