Diversity and Divergence of Dinofagellate Histone Proteins.
G3 (Bethesda). 2015 Dec 8;
Authors: Marinov GK, Lynch M
Histone proteins and the nucleosomal organization of chromatin are near-universal eukaroytic features, with the exception of dinoﬂagellates. Previous studies have suggested that histones do not play a major role in the packaging of dinoﬂagellate genomes, although several genomic and transcriptomic surveys have detected a full set of core histone genes. Here, transcriptomic and genomic sequence data from multiple dinoﬂagellate lineages are analyzed, and the diversity of histone proteins and their variants characterized, with particular focus on their potential posttranslational modiﬁcations and the conservation of the histone code. In addition, the set of putative epigenetic mark readers and writers, chromatin remodelers and histone chaperones are examined. Dinoﬂagellates clearly express the most derived set of histones among all autonomous eukaryote nuclei, consistent with a combination of relaxation of sequence con-straints imposed by the histone code and the presence of numerous specialized histone variants. The histone code itself appears to have diverged signiﬁcantly in some of its compo-nents, yet others are conserved, implying conservation of the associated biochemical processes. Speciﬁcally, and with major implications for the function of histones in dinoﬂagellates, the results presented here strongly suggest that transcription through nucleosomal arrays happens in dinoﬂagellates. Finally, the plausible roles of histones in dinoﬂagellate nuclei are discussed.
PMID: 26646152 [PubMed – as supplied by publisher]