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Author Notes:

E-mail: baek.kim@emory.edu.

J.A.H. designed experiments, collected data and wrote the paper.

J.A.H. and J.S. developed the SAMHD1 inhibitor.

J.S., S.A., X.L., L. Z. and P.L. synthesized compounds and generated triphosphates for this work.

S.T. helped with the experimental design for intracellular metabolites and performed the HPLC-MS/MS analysis.

R.W.G. provided SAMHD1 protein and helped with revising the manuscript.

J.H.N. generated the models for SAMHD1 and provided help with the writing the manuscript.

J.S., S.T., and R.F.S. provided helpful suggestions during manuscript preparation.

The authors have declared that no competing interests exist.

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Subjects:

Research Funding:

This work was supported by NIH AI049781 (B.K.), GM104198 (B.K.), and MH100999 (R.F.S.).

Keywords:

  • Science & Technology
  • Multidisciplinary Sciences
  • Hydrolysis
  • Nucleosides
  • Thin-layer chromatography
  • High performance liquid chromatography
  • Arabinose
  • Nucleotides
  • Biochemical analysis
  • Cancer treatment

Substrates and Inhibitors of SAMHD1

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Journal Title:

PLoS ONE

Volume:

Volume 12, Number 1

Publisher:

, Pages e0169052-e0169052

Type of Work:

Article | Final Publisher PDF

Abstract:

SAMHD1 hydrolyzes 2′-deoxynucleoside-5′-triphosphates (dNTPs) into 2′-deoxynucleosides and inorganic triphosphate products. In this paper, we evaluated the impact of 2′ sugar moiety substitution for different nucleotides on being substrates for SAMHD1 and mechanisms of actions for the results. We found that dNTPs ((2′R)-2′-H) are only permissive in the catalytic site of SAMHD1 due to L150 exclusion of (2′R)-2′-F and (2′R)-2′-OH nucleotides. However, arabinose ((2′S)-2′-OH) nucleoside-5′-triphosphates analogs are permissive to bind in the catalytic site and be hydrolyzed by SAMHD1. Moreover, when the (2′S)-2′ sugar moiety is increased to a (2′S)-2′-methyl as with the SMDU-TP analog, we detect inhibition of SAMHD1's dNTPase activity. Our computational modeling suggests that (2′S)-2′-methyl sugar moiety clashing with the Y374 of SAMHD1. We speculate that SMDU-TP mechanism of action requires that the analog first docks in the catalytic pocket of SAMHD1 but prevents the A351-V378 helix conformational change from being completed, which is needed before hydrolysis can occur. Collectively we have identified stereoselective 2′ substitutions that reveal nucleotide substrate specificity for SAMHD1, and a novel inhibitory mechanism for the dNTPase activity of SAMHD1. Importantly, our data is beneficial for understanding if FDA-approved antiviral and anticancer nucleosides are hydrolyzed by SAMHD1 in vivo.

Copyright information:

© 2017 Hollenbaugh et al.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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