UCSF

Evolutionary innovations in chromatin biology have been recently discovered through the study of fungi. In Saccharomyces cerevisiae, a prion form of a deacetylase complex assembles over subtelomeric domains that produces a heritable gene expression state that enables resistance to stress. In Candida albicans, stress triggers adaptive chromosome destabilization via erasure a centromeric histone H3, CENP-A; a process that cooperates with a newly evolved H2A variant lacking a mitotic phosphorylation site. Finally, in Cryptococcus neoformans, the loss of a cytosine DNA methyltransferase at least 50 million years ago has enabled the Darwinian evolution of methylation patterns over geological timescales. These studies reveal a remarkable genetic and epigenetic evolutionary plasticity of the chromatin fiber, despite the highly conserved structure of the nucleosome.