Download MendeleyMechanism of Allosteric Activation of Samhd1 by Dgtp
Ji, X., Wu, Y., Yan, J., Mehrens, J., Yang, H., Delucia, M., Hao, C., Gronenborn, A.M., Skowronski, J., Ahn, J., Xiong, Y.(2013) Nat Struct Mol Biol 20: 1304
- PubMed: 24141705
- DOI: https://doi.org/10.1038/nsmb.2692
- Primary Citation of Related Structures:
4BZB, 4BZC - PubMed Abstract:
SAMHD1, a dNTP triphosphohydrolase (dNTPase), has a key role in human innate immunity. It inhibits infection of blood cells by retroviruses, including HIV, and prevents the development of the autoinflammatory Aicardi-Goutières syndrome (AGS). The inactive apo-SAMHD1 interconverts between monomers and dimers, and in the presence of dGTP the protein assembles into catalytically active tetramers. Here, we present the crystal structure of the human tetrameric SAMHD1-dGTP complex. The structure reveals an elegant allosteric mechanism of activation through dGTP-induced tetramerization of two inactive dimers. Binding of dGTP to four allosteric sites promotes tetramerization and induces a conformational change in the substrate-binding pocket to yield the catalytically active enzyme. Structure-based biochemical and cell-based biological assays confirmed the proposed mechanism. The SAMHD1 tetramer structure provides the basis for a mechanistic understanding of its function in HIV restriction and the pathogenesis of AGS.
Organizational Affiliation:
1] Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA. [2].
