Computational Biology
@ Comenius University in Bratislava

Broňa Brejová, Viktória Hodorová, Hana Lichancová, Askar Gafurov, Dominik Bujna, Filip Brázdovič, Filip Červenák, Tomáš Petrík, Eva Hegedűsová, Michaela Forgáčová Jakúbková, Martina Neboháčová, Ľubomír Tomáška, Matthias Sipiczki, Tomáš Vinař, Jozef Nosek. Noncanonical chromosomal-end-specific telomeric arrays in naturally telomerase-negative yeasts. Technical Report 2025.09.07.674783, bioRxiv, 2025.

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Download from publisher: https://doi.org/10.1101/2025.09.07.674783

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Abstract:

In most eukaryotes, chromosomal DNA terminates with tandem repeats of a 
short G-rich motif, such as the canonical TTAGGG sequence. The arrays of 
telomeric repeats are maintained by telomerase or by alternative lengthening 
of telomeres (ALT). Here we report that nuclear chromosomes of several 
basidiomycetous yeasts classified into the order Microstromatales carry 
unusual telomeres. We demonstrate that instead of TTAGGG-like repeats these 
telomeres are composed of unique tandem arrays which are in most cases 
specific to a particular chromosomal end. In contrast to other 
basidiomycetes, the Microstromatales genomes lack orthologs coding for the 
telomerase catalytic subunit Est2 and a shelterin component Tpp1 indicating 
that noncanonical telomeric arrays are maintained by a telomerase-
independent mechanism. We hypothesize that in a common ancestor of 
Microstromatales the loss of telomerase and Tpp1 was compensated by 
activation of an ALT mechanism, which promoted amplification of various 
motifs and formation of distinct telomeric arrays at most chromosomal ends.