The YEATS domain containing protein PyYEATS functions as a histone acetylation reader in the red seaweed Pyropia yezoensis

Pyropia yezoensis, a key economic marine crop in Asia, serves as a model for red seaweed research. Previously, we determined that histone acetylation plays essential roles in the response to abiotic stresses and the formation of asexual spores in P. yezoensis. However, the reader proteins of acetylated histones remain to be identified. In this study, we characterized the gene encoding a YEATS domain-containing protein (PyYEATS) in P. yezoensis. The PyYEATS protein, mainly localized in nuclei with a small amount in cytosolic fractions in thalli, harbored a classic YEATS domain followed by a coiled-coil domain at the C-terminal. This locus exhibited conservation in domain structure compared with its homologs in other red algae and showed a closer relationship to animal GAS41 counterparts than plant YAFs. In vitro assays showed that the PyYEATS protein preferentially binds H3K14ac, H3K18ac, and H4K5ac and that the F105, W124, and F127 residues in the YEATS domain are essential for its affinity to these histone acetylation sites. Y2H and GST-pulldown approaches revealed an interaction of PyYEATS with S-adenosyl-L-homocysteine hydrolase (SAHase), eukaryotic translation initiation factor 3 (eIF3), and actin, among others, suggesting possible extra-transcriptional functions for PyYEATS. Finally, we observed that the transcript levels of this gene significantly increased after wounding in P. yezoensis thalli, pointing out a potential role in the P. yezoensis stress response. Our findings provide important insights into the evolution of chromatin readers of histone acetylation in red seaweeds and help to shed light on the biological function exerted by PyYEATS in this species.