SUMOylated proteins were found to be predominantly nuclear, and involved in chromatin remodelling, RNA splicing, transcription and DNA repair. When compared with other SUMOylation studies, a significant overlap with PRISM-identified SUMO sites (48%) and SUMO target proteins (85%) was confirmed. We discovered one-fifth of the PRISM-identified SUMOylated lysines to overlap with ubiquitylation and acetylation.
My comment: SUMOylation appears to be a new name for RNA-directed DNA methylation, which links nutrient-dependent RNA-mediated amino acid substitutions and the physiology of reproduction to cell type differentiation in all cells of all individuals of all genera. The overlap with ubiquitylation and acetylation may be confusing to theorists who have not learned how ecological variation is linked to ecological adaptations via nutrient-dependent DNA repair.
Reported as: Technique to identify system-wide post-translational modification sites
SUMOylation is a reversible post-translational modification (PTM) regulating all nuclear processes. Identification of SUMOylation sites by mass spectrometry (MS) has been hampered by bulky tryptic fragments, which thus far necessitated the use of mutated SUMO.
Authors present a SUMO-specific protease-based methodology which circumvents this problem, dubbed Protease-Reliant Identification of SUMO Modification (PRISM).
PRISM allows for detection of SUMOylated proteins as well as identification of specific sites of SUMOylation while using wild-type SUMO. The method is generic and could be widely applied to study lysine PTMs.
Authors employ PRISM in combination with high-resolution MS to identify SUMOylation sites from HeLa cells under standard growth conditions and in response to heat shock. They identified 751 wild-type SUMOylation sites on endogenous proteins, including 200 dynamic SUMO sites in response to heat shock.
My comment: Some people may not realize that nutrient stress and social stress are linked from the epigenetic landscape to the physical landscape of DNA via RNA-mediated amino acid substitutions that stabilize organized genomes in the context of DNA repair during thermodynamic cycles of protein biosynthesis and degradation.