Česká společnost pro hmotnostní spektrometrii

(13. ročník České konference hmotnostní spektrometrie a 11. Neformální proteomické setkání - ThO-13)
No Mark, No Problem: Alternative Epigenetic Silencing in Algae

Gabriela Lochmanová ^1,2 *, Palina Ryzhaya ^1,2, Rafal Krela ³, María Carbó ³, Zbyněk Zdráhal ^1,2, Kateřina Bišová ⁴, Iva Mozgová ³

1. Central European Institute of Technology, Masaryk Univerzity, Brno, Czech Republic
2. Faculty of Science, Masaryk University, Brno, Czech Republic
3. Biology Centre - Institute of Plant Molecular Biology, CAS, České Budějovice, Czech Republic
4. Institute of Microbiology – Centre Algatech, CAS, Třeboň, Czech Republic

Abstrakt

Precise timing of gene expression is crucial for transitions between developmental stages in eukaryotic organisms. Polycomb Repressive Complexes (PRCs) play a key role in specifying cell identity and act as central epigenetic regulators in multicellular development. Among them, PRC2 is a multi-subunit histone methyltransferase that catalyzes the trimethylation of lysine 27 on histone H3 (H3K27me3), a conserved mark of facultative heterochromatin. In plants, PRC2 loss leads to severe developmental defects, while in humans, its dysregulation is linked to various diseases, including cancer, neurodegenerative disorders, and developmental defects. These observations support the long-standing view that PRC2 is both essential and evolutionarily conserved across eukaryotes.

However, our recent findings challenge this assumption. Using mass spectrometry-based proteomics—including data-dependent acquisition and parallel reaction monitoring—we examined post-translational modifications in histone extracts and pull-down samples of selected algal species. Surprisingly, H3K27me3 was not detected in certain algae, suggesting the existence of alternative mechanisms for facultative heterochromatin formation that differ from those in land plants.

These results reveal previously hidden evolutionary divergence in PRC2 composition and function, particularly within the diverse algal lineage, and raise new questions about the molecular mechanisms underlying epigenetic silencing in these species.

* Korespondující autor: gabriela.lochmanova@ceitec.muni.cz

Poděkování:

This research was supported by Czech Science Foundation (project No. 25-17578S). CIISB, Instruct-CZ Centre of Instruct-ERIC EU consortium, funded by MEYS CR infrastructure project LM2023042 and European Regional Development Fund-Project "Innovation of Czech Infrastructure for Integrative Structural Biology "(No. CZ.02.01.01/00/23_015/0008175), is gratefully acknowledged for the financial support of the measurements at the CEITEC Proteomics Core Facility. Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by MEYS CR.