Crystal structure of the hinge domain of Smchd1 reveals its dimerization mode and nucleic acid-binding residues

Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) is an epigenetic regulator in which polymorphisms cause the human developmental disorder, Bosma arhinia micropthalmia syndrome, and the degenerative disease, facioscapulohumeral muscular dystrophy. SMCHD1 is considered a noncanonical SMC family member because its hinge domain is C-terminal, because it homodimerizes rather than heterodimerizes, and because SMCHD1 contains a GHKL-type, rather than an ABC-type ATPase domain at its N terminus. The hinge domain has been previously implicated in chromatin association; however, the underlying mechanism involved and the basis for SMCHD1 homodimerization are unclear. Here, we used x-ray crystallography to solve the three-dimensional structure of the Smchd1 hinge domain. Together with structure-guided mutagenesis, we defined structural features of the hinge domain that participated in homodimerization and nucleic acid binding, and we identified a functional hotspot required for chromatin localization in cells. This structure provides a template for interpreting the mechanism by which patient polymorphisms within the SMCHD1 hinge domain could compromise function and lead to facioscapulohumeral muscular dystrophy.

Source: Signal Transduction Knowledge Environment - June 15, 2020 Category: Science Authors: Chen, K., Birkinshaw, R. W., Gurzau, A. D., Wanigasuriya, I., Wang, R., Iminitoff, M., Sandow, J. J., Young, S. N., Hennessy, P. J., Willson, T. A., Heckmann, D. A., Webb, A. I., Blewitt, M. E., Czabotar, P. E., Murphy, J. M. Tags: STKE Research Articles Source Type: news