How do centromeres evolve ?

The seminar will take place on Monday 18 May at LGDP.

Zoom link : https://inrae-fr.zoom.us/j/6035424594? 

Abstract

Centromeres evolved at the root of eukaryotes to segregate chromosomes during cell division. Despite their ancient origin and essential function, centromeric DNA sequences evolve rapidly and adopt a diversity of architectures, including point centromeres, satellite arrays, transposon clusters, and holocentrics.

To analyse centromere evolution at a broad phylogenetic scale, we characterised architectures across 327 diverse Darwin Tree of Life genome assemblies. Centromere architecture was uncorrelated with phylogenetic relatedness, with similar configurations arising independently across divergent lineages. We modelled centromeric evolution as a cycle, in which satellite and transposon-based architectures interconvert, with independent origins of holocentricity. We curated >23 million centromeric satellite repeats comprising 284 families from 176 species.

Despite high sequence divergence between satellite families, higher-order repeats are conserved across species, indicating functional constraint at the level of repeat architecture, rather than primary base sequence. The satellite arrays are heavily invaded by diverse transposon families, which are overall enriched for retroelements, consistent with multiple convergent adaptations to the centromeric niche.

In 89 species, transposons themselves constitute the primary centromere structure. We further observed centrophilic transposons forming tandem arrays and higher order repeats, suggesting a mechanism for satellite regeneration. Our sample includes at least five independent origins of holocentricity in plants and animals, which have varying association with periodic satellite arrays. We propose that sequence instability and meiotic drive promote turnover of centromere states, driving repeated architectural interconversions during evolution.

Contact

If you would like to meet Ian during his visit, please contact marie.mirouze@ird.fr