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A dual-anchoring mechanism for the hemimethylated CG-guided histone ubiquitylation

ABSTRACT: Maintenance of plant CG DNA methylation is critically regulated by VIM proteins, a family of SRA domain-containing E3 ligases that read hemimethylated CG (hemiCG) sites and modulate the MET1-mediated DNA methylation on chromatin. How VIM proteins bridge the hemiCG readout with their ubiquitylation activity remains unclear. Here we report the structure-function characterization of VIM1-mediated ubiquitylation on hemiCG-containing nucleosomes, revealing H3 and H4 both as the substrates of VIM1. We find that VIM1 is anchored to nucleosome via both the SRA and RING domains, with the interaction between the RING2 domain and H2A-H2B acidic patch important for the nucleosome tethering and the SRA-hemiCG interaction critical for enzymatic catalysis. Formation of a helical bundle between the RING1 and RING2 domains of VIM1 further creates a platform for cooperative VIM1-E2-nucleosome binding. Such a dual nucleosome anchoring by the SRA and RING modules underpins hemiCG-dependent VIM1-substrate assembly, permitting persistent yet context- dependent H3/H4 ubiquitylation.

INSTRUMENT(S):

ORGANISM(S): Xenopus Laevis (african Clawed Frog)

SUBMITTER: Zhongwen Cao

LAB HEAD: Dr.Yinsheng Wang, Dr.Jikui Song

PROVIDER: PXD079072 | Pride | 2026-05-30

REPOSITORIES: Pride

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			Action	DRS
	GlyGlySites.txt	Txt
	Xinyi1.raw	Raw
	Xinyi1_-40.mzXML	Mzxml
	Xinyi1_-60.mzXML	Mzxml
	Xinyi1_-80.mzXML	Mzxml

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