Telomere length regulation by Rif1 protein from Hansenula polymorpha.

Alexander N Malyavko,Olga A Petrova,Vladimir I Polshakov,Olga A Dontsova,Maria I Zvereva

doi:10.7554/elife.75010

Alexander N Malyavko, Olga A Petrova + Show 3 more

Open Access

https://doi.org/10.7554/elife.75010

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Abstract

Rif1 is a large multifaceted protein involved in various processes of DNA metabolism - from telomere length regulation and replication to double-strand break repair. The mechanistic details of its action, however, are often poorly understood. Here, we report functional characterization of the Rif1 homologue from methylotrophic thermotolerant budding yeast Hansenula polymorpha DL-1. We show that, similar to other yeast species, H. polymorpha Rif1 suppresses telomerase-dependent telomere elongation. We uncover two novel modes of Rif1 recruitment at H. polymorpha telomeres: via direct DNA binding and through the association with the Ku heterodimer. Both of these modes (at least partially) require the intrinsically disordered N-terminal extension - a region of the protein present exclusively in yeast species. We also demonstrate that Rif1 binds Stn1 and promotes its accumulation at telomeres in H. polymorpha.

Highlights

Chromosomes of most eukaryotic organisms end in distinctive nucleoprotein structures, called telomeres, which are essential for protection of chromosomes from degradation and fusions by the DNA repair machinery (de Lange, 2018)
We found that Rif1 from the methylotrophic yeast H. polymorpha prevents hyperelongation of telomeres, similar to its other yeast counterparts
Telomerase-d ependent telomere overelongation can be observed in the strains with either deletion of the RIF1 gene, or mutations that disrupt Rap1-telomere association (Hardy et al, 1992; Shi et al, 2013; Teng et al, 2000)

Summary

Introduction

Chromosomes of most eukaryotic organisms end in distinctive nucleoprotein structures, called telomeres, which are essential for protection of chromosomes from degradation and fusions by the DNA repair machinery (de Lange, 2018). Short G/C-rich telomeric DNA repeats provide a platform for loading of a specific set of telomeric proteins forming complex dynamic assemblies at the ends of the chromosomes. Dividing cells are constantly losing telomeric repeats due to incomplete replication unless counteracted by either recombination or activity of the ribonucleoprotein complex telomerase. Replenishing of telomeric DNA by telomerase is crucial for long-term proliferation of the majority of Malyavko et al eLife 2022;11:e75010.

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