Systematic analysis of linker histone PTM hotspots reveals phosphorylation sites that modulate homologous recombination and DSB repair.

Systematic analysis of linker histone PTM hotspots reveals phosphorylation sites that modulate homologous recombination and DSB repair. DNA Repair (Amst). 2019 Nov 29;86:102763 Authors: Mukherjee K, English N, Meers C, Kim H, Jonke A, Storici F, Torres M Abstract Double strand-breaks (DSBs) of genomic DNA caused by ionizing radiation or mutagenic chemicals are a common source of mutation, recombination, chromosomal aberration, and cell death. Linker histones are DNA packaging proteins with established roles in chromatin compaction, gene transcription, and in homologous recombination (HR)-mediated DNA repair. Using a machine-learning model for functional prioritization of eukaryotic post-translational modifications (PTMs) in combination with genetic and biochemical experiments with the yeast linker histone, Hho1, we discovered that site-specific phosphorylation sites regulate HR and HR-mediated DSB repair. Five total sites were investigated (T10, S65, S141, S173, and S174), ranging from high to low function potential as determined by the model. Of these, we confirmed S173/174 are phosphorylated in yeast by mass spectrometry and found no evidence of phosphorylation at the other sites. Phospho-nullifying mutations at these two sites results in a significant decrease in HR-mediated DSB repair templated either with oligonucleotides or a homologous chromosome, while phospho-mimicing mutations have no effect. S65, corresponding to a mammali...
Source: DNA Repair - Category: Genetics & Stem Cells Authors: Tags: DNA Repair (Amst) Source Type: research