PMID: 21489993
Nady N, Lemak A, Walker JR, Avvakumov GV, Kareta MS, Achour M, Xue S, Duan S, Allali-Hassani A, Zuo X, Wang YX, Bronner C, Chedin F, Arrowsmith CH, Dhe-Paganon S
Recognition of multivalent histone states associated with heterochromatin by UHRF1.
J Biol Chem. 2011 Apr 13.
Histone modifications and DNA methylation represent two layers of heritable epigenetic information that regulate eukaryotic chromatin structure and gene activity. UHRF1 is a unique factor that bridges these two layers; it is required for maintenance DNA methylation at hemi-methylated CpG sites which are specifically recognized through its SRA domain and also interacts with histone H3 trimethylated on lysine 9 (H3K9me3) in an unspecified manner. Here we show that UHRF1 contains a Tandem Tudor Domain (TTD) that recognizes H3 tail peptides with the heterochromatin-associated modification state of trimethylated lysine 9 and unmodified lysine 4 (H3K4me0/K9me3). Solution NMR and crystallographic data reveal the TTD simultaneously recognizes H3K9me3 through a conserved aromatic cage in the first Tudor subdomain, and unmodified H3K4 within a groove between the tandem subdomains. The subdomains undergo a conformational adjustment upon peptide binding, distinct from previously reported mechanisms for dual histone mark recognition. Mutant UHRF1 protein deficient for H3K4me0/K9me3 binding shows altered localization to heterochromatic chromocenters and fails to reduce expression of a target gene, p16INK4A, when overexpressed. Our results demonstrate a novel recognition mechanism for the combinatorial readout of histone modification states associated with gene silencing, and add to the growing evidence for coordination of, and cross-talk between the modification states of H3K4 and H3K9 in regulation of gene expression.