SNAP-annotated 5mC-DNA-protein interactions: PDB entry 6c1y

PDB-id

6c1y; DSSR-derived features in text and JSON formats; DNAproDB

Class

DNA binding protein-DNA

Method

X-ray (2.3 Å)

Summary

Mbd of human mecp2 in complex with methylated DNA

Reference

Lei M, Tempel W, Chen S, Liu K, Min J (2019): "Plasticity at the DNA recognition site of the MeCP2 mCG-binding domain." Biochim Biophys Acta Gene Regul Mech, 1862, 194409. doi: 10.1016/j.bbagrm.2019.194409.

Abstract

MeCP2 is an abundant protein, involved in transcriptional repression by binding to CG and non-CG methylated DNA. However, MeCP2 might also function as a transcription activator as MeCP2 is found bound to sparsely methylated promoters of actively expressed genes. Furthermore, Attachment Region Binding Protein (ARBP), the chicken ortholog of MeCP2, has been reported to bind to Matrix/scaffold attachment regions (MARs/SARs) DNA with an unmethylated 5'-CAC/GTG-3' consensus sequence. In our previous study, although we have systemically measured the binding abilities of MBDs to unmethylated CAC/GTG DNA and the complex structures reveal that the MBD2-MBD (MBD of MBD2) binds to the unmethylated CAC/GTG DNA by recognizing the complementary GTG trinucleotide, how the MeCP2-MBD (MBD of MeCP2) recognizes the unmethylated CAC/GTG DNA, especially the MARs DNA, is still unclear. In this study, we investigated the binding characteristics of MeCP2 in recognizing unmethylated 5'-CAC/GTG-3' motif containing DNA by binding and structural studies. We found that MeCP2-MBD binds to MARs DNA with a comparable binding affinity to mCG DNA, and the MeCP2-CAC/GTG complex structure revealed that MeCP2 residues R111 and R133 form base-specific interactions with the GTG motif. For comparison, we also determined crystal structures of the MeCP2-MBD bound to mCG and mCAC/GTG DNA, respectively. Together, these crystal structures illustrate the adaptability of the MeCP2-MBD toward the GTG motif as well as the mCG DNA, and also provide structural basis of a biological role of MeCP2 as a transcription activator and its disease implications in Rett syndrome.

• The contacts include paired nucleotides (mostly a G in Watson-Crick G-C pairing) and amino-acids within a 4.5-Å distance cutoff to base atoms of 5mC.
• The structure is oriented in the base reference frame of 5mC, allowing for easy comparison and direct superimposition between entries.
• The black sphere (•) denotes the 5-methyl carbon atom in 5mC.