title: Structural basis of allosteric activation of sterile α motif and histidine-aspartate domain-containing protein 1 (SAMHD1) by nucleoside triphosphates.
abstract: Sterile α motif and histidine-aspartate domain-containing protein 1 (SAMHD1) plays a critical role in inhibiting HIV infection, curtailing the pool of dNTPs available for reverse transcription of the viral genome. Recent structural data suggested a compelling mechanism for the regulation of SAMHD1 enzymatic activity and revealed dGTP-induced association of two inactive dimers into an active tetrameric enzyme. Here, we present the crystal structures of SAMHD1 catalytic core (residues 113-626) tetramers, complexed with mixtures of nucleotides, including dGTP/dATP, dGTP/dCTP, dGTP/dTTP, and dGTP/dUTP. The combined structural and biochemical data provide insight into dNTP promiscuity at the secondary allosteric site and how enzymatic activity is modulated. In addition, we present biochemical analyses of GTP-induced SAMHD1 full-length tetramerization and the structure of SAMHD1 catalytic core tetramer in complex with GTP/dATP, revealing the structural basis of GTP-mediated SAMHD1 activation. Altogether, the data presented here advance our understanding of SAMHD1 function during cellular homeostasis.
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260.
authors.forename: Leonardus M I
authors.initials: LM
authors.lastname: Koharudin
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260.
authors.forename: Maria
authors.initials: M
authors.lastname: DeLucia
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mehrens
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260 amg100@pitt.edu.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
authors.affiliation: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260 jia12@pitt.edu.
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Ahn
mesh_terms: D000494:Allosteric Regulation; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003848:Deoxyguanine Nucleotides / Q000737:chemistry / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009690:Nucleic Acid Conformation; D043583:Nucleoside-Triphosphatase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D000076106:SAM Domain and HD Domain-Containing Protein 1
chemical_list: D003848:Deoxyguanine Nucleotides; D003854:Deoxyribonucleotides; C029603:deoxyguanosine triphosphate; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human; D043583:Nucleoside-Triphosphatase; D020559:Monomeric GTP-Binding Proteins
keywords: Enzyme Mechanism; Nucleic Acid; Protein Crystallization; SAM Domain and HD Domain-containing Protein 1 (SAMHD1); Structural Biology; X-ray Crystallography