Multi-omics Visualization of Nuclear Architecture in the Early Branching Dinoflagellate, Oxyrrhis marina

Abstract

Dinoflagellates are an abundant clade of aquatic protists with a fascinating evolutionary history that led to enigmatic features within the nucleus. It was believed that dinoflagellates lacked histones altogether, instead utilizing a variety of horizontally acquired proteins named dinoflagellate viral nucleoprotein, DVNP, and histone-like proteins, HLPs. The species Oxyrrhis marina is an early branching dinoflagellate, making its phylogenetic position evolutionally valuable to determine what features are ancestral or derived. This study aimed at a multi-omics approach to eliciting evolutionary features in O. marina. I found that the O. marina nuclear proteome contains all four canonical histones that make up the nucleosome as well as the DVNP protein. The analysis of this proteome also identified key nucleosome assembly proteins and canonical post-translational modifications along the histone’s peptides. The presence of histones and an array of nucleosome-modifying proteins suggests that the original interpretations oversimplified the elimination of histones in dinoflagellate evolution.