title: Chicken MAR-binding protein ARBP is homologous to rat methyl-CpG-binding protein MeCP2.
abstract: Here, we describe the cloning and further characterization of chicken ARBP, an abundant nuclear protein with a high affinity for MAR/SARs. Surprisingly, ARBP was found to be homologous to the rat protein MeCP2, previously identified as a methyl-CpG-binding protein. A region spanning 125 amino acids in the N-terminal halves is 96.8% identical between chicken ARBP and rat MeCP2. A deletion mutation analysis using Southwestern and band shift assays identified this highly conserved region as the MAR DNA binding domain. Alignment of chicken ARBP with rat and human MeCP2 proteins revealed six trinucleotide amplifications generating up to 34-fold repetitions of a single amino acid. Because MeCP2 was previously localized to pericentromeric heterochromatin in mouse chromosomes, we analyzed the in vitro binding of ARBP to various repetitive sequences. In band shift experiments, ARBP binds to two chicken repetitive sequences as well as to mouse satellite DNA with high affinity similar to that of its binding to chicken lysozyme MAR fragments. In mouse satellite DNA, use of several footprinting techniques characterized two high-affinity binding sites, whose sequences are related to the ARBP binding site consensus in the chicken lysozyme MAR (5'-GGTGT-3'). Band shift experiments indicated that methylation increased in vitro binding of ARBP to mouse satellite DNA two- to fivefold. Our results suggest that ARBP/MeCP2 is a multifunctional protein with roles in loop domain organization of chromatin, the structure of pericentromeric heterochromatin, and DNA methylation.
authors.affiliation: Institut für Physiologische Chemie, Universitäts-Krankenhaus Eppendorf, Hamburg, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Weitzel
authors.forename: H
authors.initials: H
authors.lastname: Buhrmester
authors.forename: W H
authors.initials: WH
authors.lastname: Strätling
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002645:Chickens; D002868:Chromosomal Proteins, Non-Histone; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D004276:DNA, Satellite / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D036961:Matrix Attachment Region Binding Proteins; D051783:Methyl-CpG-Binding Protein 2; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012332:RNA, Heterogeneous Nuclear / Q000737:chemistry* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D012097:Repressor Proteins; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: C097879:114 kDa MAR-binding protein, human; C439935:ARBP protein, chicken; D002868:Chromosomal Proteins, Non-Histone; D018076:DNA, Complementary; D004276:DNA, Satellite; D004268:DNA-Binding Proteins; D034441:Heterogeneous-Nuclear Ribonucleoproteins; C497392:MECP2 protein, human; D036961:Matrix Attachment Region Binding Proteins; C497393:Mecp2 protein, mouse; C497394:Mecp2 protein, rat; D051783:Methyl-CpG-Binding Protein 2; D009363:Neoplasm Proteins; D012332:RNA, Heterogeneous Nuclear; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins