GlcNAcylation of histone H2B facilitates its monoubiquitination

Abstract

Chromatin reorganization is governed by multiple post-translational modifications of chromosomal proteins and DNA. These histone modifications are reversible, dynamic events that can regulate DNA-driven cellular processes. However, the molecular mechanisms that coordinate histone modification patterns remain largely unknown. In metazoans, reversible protein modification by O-linked N-acetylglucosamine (GlcNAc) is catalysed by two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). However, the significance of GlcNAcylation in chromatin reorganization remains elusive. Here we report that histone H2B is GlcNAcylated at residue S112 by OGT in vitro and in living cells. Histone GlcNAcylation fluctuated in response to extracellular glucose through the hexosamine biosynthesis pathway (HBP). H2B S112 GlcNAcylation promotes K120 monoubiquitination, in which the GlcNAc moiety can serve as an anchor for a histone H2B ubiquitin ligase. H2B S112 GlcNAc was localized to euchromatic areas on fly polytene chromosomes. In a genome-wide analysis, H2B S112 GlcNAcylation sites were observed widely distributed over chromosomes including transcribed gene loci, with some sites co-localizing with H2B K120 monoubiquitination. These findings suggest that H2B S112 GlcNAcylation is a histone modification that facilitates H2BK120 monoubiquitination, presumably for transcriptional activation.

Synthetic Nucleosomes Reveal that GlcNAcylation Modulates Direct Interaction with the FACT Complex

“…As with the interactome data with the monomer, we did not see any significant enrichment of FACT upon GlcNAcylation and no BRE1A was observed. Together these data suggest a context‐dependent interaction; thus, the difference in our observations here to those published previously5c appears to lie in our use of an intact nucleosomal structure as opposed to the prior use of isolated, partially GlcNAcylated protein (this might also be due to preferential binding of isolated H2B by different histone chaperones, occluding the GlcNAcylation site).…”

Dynamic O-GlcNAcylation and its roles in the cellular stress response and homeostasis

“…It was also speculated that an E1 ubiquitin-activating enzyme interacts with Hsp70 only in its O-GlcNAcylated form (Guinez et al 2008). An agonistic relationship between these two modifications is suggested such that O-GlcNAc may alter the activity of E1 enzymes to modulate stressinduced ubiquitination (Shrikhande et al 2010;Shimura et al 2001;Fujiki et al 2011). It has also been shown that OGlcNAcylation of a protein may facilitate its subsequent ubiquitination.…”

“…It has also been shown that OGlcNAcylation of a protein may facilitate its subsequent ubiquitination. For example, O-GlcNAcylation of histone H2B at Ser112 facilitates monoubiquitination at Lys120 to regulate transcription (Fujiki et al 2011).…”

O-GlcNAcylation regulates EZH2 protein stability and function

“…First, OGT adds GlcNAc to DNA-binding transcription factors, such as p53, c-Myc, etc. (16), and to histone proteins such as histone H2A at T101, H2B at S36 and S112, H3 at S10 and T32, and H4 at S47 (17)(18)(19)(20). O-GlcNAcylation of H2B at S112 facilitates the ubiquitination of K120, leading to upregulation of transcriptional elongation (18).…”