title: Binding Analysis of Methyl-CpG Binding Domain of MeCP2 and Rett Syndrome Mutations.
abstract: Methyl-CpG binding protein 2 (MeCP2) binds to methylated cytosine in CpG island through its methyl-CpG binding domain (MBD). Here, the effects of the Rett syndrome-causing missense mutations on binding affinity of MBD to cytosine (C), methylcytosine (mC), hydroxymethylcytosine (hmC), formylcytosine (fC), and carboxylcytosine (caC) in CpG dinucleotide are investigated. MeCP2-MBD binds to mC-containing variants of double stranded CpG stronger than any other cytosine modified CpG with the strongest affinity to mC/mC. Thirteen MBD missense mutations show reduced binding affinity for mC/mC ranging with a 2-fold decrease for T158M to 88-fold for R111G. The binding affinities of these mutants to C/C are also reduced to various degrees except for T158M. Consistent with free energy perturbation analysis, correlation of binding affinity with protein unfolding allows for grouping mutations into three clusters. Correlation of the first cluster includes mutations that have a higher tendency to unfold and have lesser affinity to mC/mC and C/C. Mutations in the second cluster have similar structural stability but various affinities to mC/mC and C/C. R111G and A140V belong to the third cluster in which the loss of protein flexibility may underlie their reduction in binding affinity to mC/mC and C/C. Most notably, R111 emerges as the key structural element that modulates the specific contacts with mCpG. Implications of the results for the mCpG binding mechanism of MeCP2-MBD are discussed. These analyses provide new insights on the structure and function relationships in MeCP2-MBD and offer new clues to their roles in the pathology of Rett syndrome.
authors.affiliation: Department of Genetics and Biochemistry, Clemson University , Room 049 Life Sciences Facility 190 Collings Street, Clemson, South Carolina 29634, United States.
authors.forename: Ye
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Physics, Clemson University , 118 Kinard Laboratory Clemson, South Carolina 29634, United States.
authors.forename: Tugba G
authors.initials: TG
authors.lastname: Kucukkal
authors.affiliation: Department of Genetics and Biochemistry, Clemson University , Room 049 Life Sciences Facility 190 Collings Street, Clemson, South Carolina 29634, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Physics, Clemson University , 118 Kinard Laboratory Clemson, South Carolina 29634, United States.
authors.forename: Emil
authors.initials: E
authors.lastname: Alexov
authors.affiliation: Department of Genetics and Biochemistry, Clemson University , Room 049 Life Sciences Facility 190 Collings Street, Clemson, South Carolina 29634, United States.
authors.forename: Weiguo
authors.initials: W
authors.lastname: Cao
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D006801:Humans; D051783:Methyl-CpG-Binding Protein 2 / Q000737:chemistry / Q000378:metabolism*; D020125:Mutation, Missense; D010084:Oxidation-Reduction; D015518:Rett Syndrome / Q000235:genetics*
chemical_list: D051783:Methyl-CpG-Binding Protein 2