The mechanism of substrate-controlled allosteric regulation of SAMHD1 activated by GTP DOI

C.F. Zhu,

Wei Wei, Xin Peng

et al.

Acta Crystallographica Section D Biological Crystallography, Journal Year: 2015, Volume and Issue: 71(3), P. 516 - 524

Published: Feb. 26, 2015

SAMHD1 is the only known eukaryotic deoxynucleoside triphosphate triphosphohydrolase (dNTPase) and a major regulator of intracellular dNTP pools. It has been reported to be potent inhibitor retroviruses such as HIV-1 endogenous retrotransposons. Previous crystal structures have revealed that activated by dGTP-dependent tetramer formation. However, recent data indicated primary activator GTP, not dGTP. Therefore, how its dNTPase activity regulated needs further clarified. Here, five catalytic core in complex with different combinations GTP dNTPs are reported, including GTP-bound dimer four GTP/dNTP-bound tetramers. The show human contains two unique activator-binding sites allosteric pocket. binds one site substrate (dATP, dCTP, dUTP or dTTP) occupies other. Consequently, both required for activation enzyme. In absence binding, adopts an inactive conformation even when complexed GTP. Furthermore, concentration dNTP. Thus, level pools elegantly self-sensing ability through novel mechanism.

Language: Английский

SAMHD1 Promotes DNA End Resection to Facilitate DNA Repair by Homologous Recombination DOI Creative Commons
Waaqo Daddacha,

Allyson E. Koyen,

Amanda J. Bastien

et al.

Cell Reports, Journal Year: 2017, Volume and Issue: 20(8), P. 1921 - 1935

Published: Aug. 1, 2017

Highlights•SAMHD1 deficiency or Vpx-mediated degradation sensitizes cells to DSB-inducing agents•SAMHD1 localizes DNA double-strand breaks in response damage•SAMHD1 promotes HR and end resection independent of its dNTPase activity•SAMHD1 complexes with CtIP facilitates recruitment damage sitesSummaryDNA break (DSB) repair by homologous recombination (HR) is initiated CtIP/MRN-mediated maintain genome integrity. SAMHD1 a dNTP triphosphohydrolase, which restricts HIV-1 infection, mutations are associated Aicardi-Goutières syndrome cancer. We show that has dNTPase-independent function promoting facilitate DSB HR. causes hypersensitivity agents, recruited DSBs. via conserved C-terminal domain recruits DSBs Significantly, cancer-associated mutant impaired interaction, but not dNTPase-inactive SAMHD1, fails rescue the impairment depletion. Our findings define for HR-mediated facilitating accrual promote resection, providing insight into how integrity.Graphical abstract

Language: Английский

Citations

174
SAMHD1 shapes deoxynucleotide triphosphate homeostasis by interconnecting the depletion and biosynthesis of different dNTPs DOI Creative Commons
Claudia McCown, Corey H. Yu, Dmitri N. Ivanov

et al.

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Jan. 17, 2025

SAMHD1 is a dNTPase that impedes replication of HIV-1 in myeloid cells and resting T lymphocytes. Here we elucidate the substrate activation mechanism SAMHD1, which involves dNTP binding at allosteric sites transient tetramerization. Our findings reveal tetramerization alone insufficient to promote hydrolysis; instead, requires an inactive tetrameric intermediate with partially occupied sites. The equilibrium between active states regulates activity, driven by dissociation additional ligands preassembled tetramer. Furthermore, catalytic efficiency, but not specificity, modulated identity dNTPs occupying We show how this regulation shapes deoxynucleotide homeostasis balancing production SAMHD1-catalyzed depletion. Notably, exhibits distinct functionality, term facilitated depletion, whereby increased biosynthesis certain enhances depletion others. regulatory relationship different sheds light on emerging role biology implications for HIV/AIDS, innate antiviral immunity, cell disorders, telomere maintenance therapeutic efficacy nucleoside analogs.

Language: Английский

Citations

3
Deoxyribonucleotide metabolism, mutagenesis and cancer DOI

Christopher K. Mathews

Nature reviews. Cancer, Journal Year: 2015, Volume and Issue: 15(9), P. 528 - 539

Published: Aug. 24, 2015

Language: Английский

Citations

177
Targeting SAMHD1 with the Vpx protein to improve cytarabine therapy for hematological malignancies DOI
Nikolas Herold, Sean G. Rudd, Linda Ljungblad

et al.

Nature Medicine, Journal Year: 2017, Volume and Issue: 23(2), P. 256 - 263

Published: Jan. 9, 2017

Language: Английский

Citations

124
SAMHD1 is a single-stranded nucleic acid binding protein with no active site-associated nuclease activity DOI Creative Commons
Kyle J. Seamon,

Zhiqiang Sun,

Luda S. Shlyakhtenko

et al.

Nucleic Acids Research, Journal Year: 2015, Volume and Issue: 43(13), P. 6486 - 6499

Published: June 22, 2015

The HIV-1 restriction factor SAMHD1 is a tetrameric enzyme activated by guanine nucleotides with dNTP triphosphate hydrolase activity (dNTPase). In addition to this established activity, there have been series of conflicting reports as whether the also possesses single-stranded DNA and/or RNA 3′-5′ exonuclease activity. was purified using three chromatography steps, over which DNase largely separated from dNTPase but RNase persisted. Surprisingly, we found that catalytic and nucleotide activator site mutants no retained activities. Thus, cannot be associated any known binding site. Monomeric bind preferentially RNA, while form required for action bound weakly. ssRNA binding, not ssDNA, induces higher-order oligomeric states are distinct binds dNTPs. We conclude trace activities detected in preparations arise persistent contaminants co-purify HD active An vivo model suggested where alternates between mutually exclusive functions hydrolysis depending on pool levels presence viral ssRNA.

Language: Английский

Citations

121
Regulation of deoxynucleotide metabolism in cancer: novel mechanisms and therapeutic implications DOI Creative Commons
Rebecca Kohnken,

Karthik M. Kodigepalli,

Li Wu

et al.

Molecular Cancer, Journal Year: 2015, Volume and Issue: 14(1)

Published: Sept. 29, 2015

Regulation of intracellular deoxynucleoside triphosphate (dNTP) pool is critical to genomic stability and cancer development. Imbalanced dNTP pools can lead enhanced mutagenesis cell proliferation resulting in Therapeutic agents that target synthesis metabolism are commonly used treatment several types cancer. Despite studies, the molecular mechanisms regulate levels maintain their homeostasis not completely understood. The discovery SAMHD1 as first mammalian triphosphohydrolase provided new insight into regulation. maintains homeostatic DNA replication damage repair. Recent progress indicates gene mutations epigenetic downregulation activity or expression multiple cancers. Impaired function cause increased instability cell-cycle progression, thereby facilitating proliferation. This review summarizes latest advances understanding importance development novel regulating this process.

Language: Английский

Citations

108
Heterozygous colon cancer-associated mutations of SAMHD1 have functional significance DOI Open Access
Matilda Rentoft, Kristoffer Lindell, Phong Tran

et al.

Proceedings of the National Academy of Sciences, Journal Year: 2016, Volume and Issue: 113(17), P. 4723 - 4728

Published: April 11, 2016

Significance The three major DNA replication fidelity determinants are nucleotide selectivity, proofreading, and mismatch repair. Defects in the two latter now firmly associated with cancer. Nucleotide selectivity is affected by changes absolute or relative concentrations of dNTPs. Here, we show that hemizygous SAMHD1 +/− mouse embryos have increased dNTP pools compared wild-type controls heterozygous mutations inactivate frequently found colon cancers. We infer such cancer cells and, therefore, higher mutation rates. These observations suggest concentrations, which affect first determinant fidelity,

Language: Английский

Citations

108
Phospho-dependent Regulation of SAMHD1 Oligomerisation Couples Catalysis and Restriction DOI Creative Commons
Laurence Arnold, Harriet C. T. Groom, Simone Kunzelmann

et al.

PLoS Pathogens, Journal Year: 2015, Volume and Issue: 11(10), P. e1005194 - e1005194

Published: Oct. 2, 2015

SAMHD1 restricts HIV-1 infection of myeloid-lineage and resting CD4+ T-cells. Most likely this occurs through deoxynucleoside triphosphate triphosphohydrolase activity that reduces cellular dNTP to a level where reverse transcriptase cannot function, although alternative mechanisms have been proposed recently. Here, we present combined structural virological data demonstrating in addition allosteric activation activity, restriction correlates with the capacity form "long-lived" enzymatically competent tetramers. Tetramer disruption invariably abolishes but has varied effects on vitro activity. phosphorylation also ablates tetramer formation without affecting steady-state kinetics. However phospho-SAMHD1 is unable catalyse turnover under conditions nucleotide depletion. Based our findings propose model for phosphorylation-dependent regulation dephosphorylation switches housekeeping found cycling cells high-activity stable tetrameric depletes maintains low levels dNTPs differentiated cells.

Language: Английский

Citations

106
SAMHD1-mediated HIV-1 restriction in cells does not involve ribonuclease activity DOI
Jenna M. Antonucci,

Corine St. Gelais,

Suresh de Silva

et al.

Nature Medicine, Journal Year: 2016, Volume and Issue: 22(10), P. 1072 - 1074

Published: Oct. 1, 2016

Language: Английский

Citations

88
SAMHD1 Functions and Human Diseases DOI Creative Commons
Si’Ana A. Coggins, Bijan Mahboubi, Raymond F. Schinazi

et al.

Viruses, Journal Year: 2020, Volume and Issue: 12(4), P. 382 - 382

Published: March 31, 2020

Deoxynucleoside triphosphate (dNTP) molecules are essential for the replication and maintenance of genomic information in both cells a variety viral pathogens. While process dNTP biosynthesis by cellular enzymes, such as ribonucleotide reductase (RNR) thymidine kinase (TK), has been extensively investigated, negative regulatory mechanism pools was recently found to involve sterile alpha motif (SAM) domain histidine-aspartate (HD) domain-containing protein 1, SAMHD1. When active, triphosphohydrolase activity SAMHD1 degrades dNTPs into their 2'-deoxynucleoside (dN) subparts, steadily depleting intercellular pools. The differential expression levels activation states various cell types contributes unique that either aid (i.e., dividing T cells) or restrict nondividing macrophages) consumes dNTPs. Genetic mutations induce rare inflammatory encephalopathy called Aicardi-Goutières syndrome (AGS), which phenotypically resembles infection. Recent publications have identified diverse roles double-stranded break repair, genome stability, stress response through interferon signaling. Finally, series were also reported cancer while why is mutated these remains investigated. Here, we reviewed studies begun illuminating highly virology, immunology, biology.

Language: Английский

Citations

82