6mw7 | pdb_00006mw7
Crystal structure of ATPase module of SMCHD1 bound to ATP
Structural highlights
Disease[SMHD1_HUMAN] Hyposmia-nasal and ocular hypoplasia-hypogonadotropic hypogonadism syndrome;Facioscapulohumeral dystrophy. The disease is caused by mutations affecting the gene represented in this entry. SMCHD1 mutations lead to DUX4 expression in somatic tissues, including muscle cells, when an haplotype on chromosome 4 is permissive for DUX4 expression (PubMed:23143600). Ectopic expression of DUX4 in skeletal muscle activates the expression of stem cell and germline genes, and, when overexpressed in somatic cells, DUX4 can ultimately lead to cell death (PubMed:23143600). FSHD2 and FSHD1 share a common pathophysiological pathway in which the FSHD2 gene SMCHD1 can act as a modifier for disease severity in families affected by FSHD1 (PubMed:24075187, PubMed:25370034).[1] [2] [3] The disease is caused by mutations affecting the gene represented in this entry. Function[SMHD1_HUMAN] Non-canonical member of the structural maintenance of chromosomes (SMC) protein family that plays a key role in epigenetic silencing by regulating chromatin architecture (By similarity). Promotes heterochromatin formation in both autosomes and chromosome X, probably by mediating the merge of chromatin compartments (By similarity). Plays a key role in chromosome X inactivation in females by promoting the spreading of heterochromatin (PubMed:23542155). Recruited to inactivated chromosome X by Xist RNA and acts by mediating the merge of chromatin compartments: promotes random chromatin interactions that span the boundaries of existing structures, leading to create a compartment-less architecture typical of inactivated chromosome X (By similarity). Required to facilitate Xist RNA spreading (By similarity). Also required for silencing of a subset of clustered autosomal loci in somatic cells, such as the DUX4 locus (PubMed:23143600). Has ATPase activity; may participate in structural manipulation of chromatin in an ATP-dependent manner as part of its role in gene expression regulation (PubMed:29748383). Also plays a role in DNA repair: localizes to sites of DNA double-strand breaks in response to DNA damage to promote the repair of DNA double-strand breaks (PubMed:25294876, PubMed:24790221). Acts by promoting non-homologous end joining (NHEJ) and inhibiting homologous recombination (HR) repair (PubMed:25294876).[UniProtKB:Q6P5D8][4] [5] [6] [7] [8] Publication Abstract from PubMedVariants in the gene SMCHD1, which encodes an epigenetic repressor, have been linked to both congenital arhinia and a late-onset form of muscular dystrophy called facioscapulohumeral muscular dystrophy type 2 (FSHD2). This suggests that SMCHD1 has a diversity of functions in both developmental time and space. The C-terminal end of SMCHD1 contains an SMC-hinge domain which mediates homodimerization and chromatin association, whereas the molecular architecture of the N-terminal region, which harbors the GHKL-ATPase domain, is not well understood. We present the crystal structure of the human SMCHD1 N-terminal ATPase module bound to ATP as a functional dimer. The dimer is stabilized by a novel N-terminal ubiquitin-like fold and by a downstream transducer domain. While disease variants map to what appear to be critical interdomain/intermolecular interfaces, only the FSHD2-specific mutant constructs we tested consistently abolish ATPase activity and/or dimerization. These data suggest that the full functional profile of SMCHD1 has yet to be determined. A ubiquitin-like domain is required for stabilizing the N-terminal ATPase module of human SMCHD1.,Pedersen LC, Inoue K, Kim S, Perera L, Shaw ND Commun Biol. 2019 Jul 10;2:255. doi: 10.1038/s42003-019-0499-y. eCollection 2019. PMID:31312724[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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