Protein acetylation regulates the wound-induced asexual spore formation in Pyropia yezoensis

Lysine acetylation (LysAc) of proteins plays critical regulatory roles in a wide range of biological processes in both prokaryotes and eukaryotes. However, characteristics of LysAc and related proteins in red algae have not been investigated. In a marine aquaculture species Pyropia yezoensis, thallus cells form and release asexual spores under wound stress, and this process provides an essential source of seedlings in aquaculture. In order to elucidate the underlying regulatory mechanisms during spore formation, we performed a global acetylproteome analysis in both intact and wounded thalli. A total of 4647 LysAc sites were identified on 1398 proteins. Among them, 361 proteins exhibited differential acetylations (DAPs) at the time of sporangia formation and 382 at the time of spore maturation. Functional classification of all the DAPs revealed that they were primarily associated with central metabolic pathways, highlighting the importance of lysine acetylation in asexual spore formation. Particularly, >30 proteins related to photosynthesis and carbon fixation showed coordinated decline, consistent with the repressed photosynthetic efficiency after wounding. Starch was accumulated and the LysAc on the catalytic domain of starch synthase significantly increased during spore formation. Proteins related to cytoskeleton remodeling also had variations in LysAc, aligning with the observed depolymerization of microfilaments in spores. Our study provides not only fundamental information in protein acetylation in Pyropia as a prominent example for red seaweeds but also valuable insights on the post-translational regulation in wound-induced spore formation.