Polycomb protein Cbx4 promotes SUMO modification of de novo DNA methyltransferase Dnmt3a.

The 'de novo methyltransferase' Dnmt3a (DNA methyltransferase 3a) has been shown to mediate transcriptional repression. Post-translational modification of Dnmt3a by SUMOylation affects its ability to transcriptionally repress. However, very little is known about how the SUMOylation process is regulated. In the present study, we identified a PcG (Polycomb group) protein, ...
Cbx4 (chromobox 4), as a specific interaction partner of Dnmt3a. Co-expression of Cbx4 and SUMO-1 (small ubiquitin-related modifier-1) along with Dnmt3a in transfected cells results in enhanced modification of Dnmt3a with SUMO-1. Purified Cbx4 also promotes SUMOylation of Dnmt3a in vitro. The modification occurs in the N-terminal regulatory region, including the PWWP (Pro-Trp-Trp-Pro) domain. Our results suggest that Cbx4 functions as a SUMO E3 ligase for Dnmt3a and it might be involved in the functional regulation of DNA methyltransferases by promoting their SUMO modification.
Mesh Terms:
Amino Acid Sequence, Animals, Cells, Cultured, DNA (Cytosine-5-)-Methyltransferase, DNA Methylation, Heterochromatin, Humans, Mice, Molecular Sequence Data, Protein Structure, Tertiary, Repressor Proteins, SUMO-1 Protein, Sequence Alignment, Transfection, Ubiquitin-Protein Ligases
Biochem. J.
Date: Jul. 15, 2007
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