Telomerase RNA gene paralogs in plants – the usual pathway to unusual telomeres

Michal Závodník, Petr Fajkus, Michal Franek, David Kopecký, Sònia Garcia, Steven Dodsworth, Andrés Orejuela, Agata Kilar, Jiří Ptáček, Martin Mátl, Anna Hýsková, Jiří Fajkus, Vratislav Peška

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Abstract

Telomerase, telomeric DNA and associated proteins together represent a complex, finely tuned and functionally conserved mechanism that ensures genome integrity by protecting and maintaining chromosome ends. Changes in its components can threaten an organism's viability. Nevertheless, molecular innovation in telomere maintenance has occurred multiple times during eukaryote evolution, giving rise to species/taxa with unusual telomeric DNA sequences, telomerase components or telomerase-independent telomere maintenance. The central component of telomere maintenance machinery is telomerase RNA (TR) as it templates telomere DNA synthesis, its mutation can change telomere DNA and disrupt its recognition by telomere proteins, thereby leading to collapse of their end-protective and telomerase recruitment functions.

Using a combination of bioinformatic and experimental approaches, we examine a plausible scenario of evolutionary changes in TR underlying telomere transitions.

We identified plants harbouring multiple TR paralogs whose template regions could support the synthesis of diverse telomeres. In our hypothesis, formation of unusual telomeres is associated with the occurrence of TR paralogs that can accumulate mutations, and through their functional redundancy, allow for the adaptive evolution of the other telomere components.

Experimental analyses of telomeres in the examined plants demonstrate evolutionary telomere transitions corresponding to TR paralogs with diverse template regions.
Original languageEnglish
Number of pages14
JournalNew Phytologist
Early online date30 Jun 2023
DOIs
Publication statusEarly online - 30 Jun 2023

Keywords

  • evolution
  • land plants
  • mechanism of telomere transitions
  • telomerase RNA paralogs
  • unusual telomere DNA

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