The Histone Chaperone Network Is Highly Conserved in Physarum polycephalum

Area of Science:

• Molecular Biology
• Eukaryotic Evolution
• Chromatin Biology

Background:

• Nucleosomes, formed by histones and DNA, require histone chaperones for proper chromatin assembly.
• Histone chaperones escort histones throughout their cellular lifecycle, ensuring correct DNA incorporation.
• Physarum polycephalum, an early-branching eukaryote, exhibits conserved histones, prompting investigation into its histone chaperones.

Purpose of the Study:

• To investigate the conservation and evolution of histone chaperones in Physarum polycephalum.
• To compare Physarum histone chaperones with those found in animals and plants.
• To understand the role of histone chaperones in an early-divergent eukaryotic lineage.

Main Methods:

• Comparative genomic analysis of histone chaperone genes in Physarum polycephalum.
• Identification and structural comparison of histone chaperone domains and key residues.
• RNA sequencing to analyze chaperone gene expression during the cell cycle in Physarum.

Main Results:

• Most known histone chaperones and their functional domains are conserved in Physarum.
• Physarum histone chaperones show structural similarities to plant orthologues (PpHIRA, PpCABIN1, PpSPT6) and yeast complexes (PpFACT).
• The Physarum genome encodes the animal-specific APFL chaperone, and distinct cell cycle expression patterns for chaperones were observed during S-phase.

Conclusions:

• Histone chaperones play a conserved role in histone management in Physarum polycephalum, an early-branching eukaryote.
• The study highlights the evolutionary conservation of histone chaperone machinery across diverse eukaryotic lineages.
• Physarum serves as a model to understand the evolution of chromatin assembly factors.