Impaired dNTPase activity of SAMHD1 by phosphomimetic mutation of Thr-592

Chenxiang Tang; Xiaoyun Ji; Li Wu; Yong Xiong

doi:10.1074/jbc.m115.677435

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Impaired dNTPase activity of SAMHD1 by phosphomimetic mutation of Thr-592

Journal article

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Impaired dNTPase activity of SAMHD1 by phosphomimetic mutation of Thr-592

Chenxiang Tang, Xiaoyun Ji, Li Wu and Yong Xiong

The Journal of biological chemistry, Vol.290(44), pp.26352-26359

10/30/2015

DOI: 10.1074/jbc.m115.677435

PMCID: PMC4646291

PMID: 26294762

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Abstract

SAMHD1 is a cellular protein that plays key roles in HIV-1 restriction and regulation of cellular dNTP levels. Mutations in SAMHD1 are also implicated in the pathogenesis of chronic lymphocytic leukemia and Aicardi-Goutières syndrome. The anti-HIV-1 activity of SAMHD1 is negatively modulated by phosphorylation at residue Thr-592. The mechanism underlying the effect of phosphorylation on anti-HIV-1 activity remains unclear. SAMHD1 forms tetramers that possess deoxyribonucleotide triphosphate triphosphohydrolase (dNTPase) activity, which is allosterically controlled by the combined action of GTP and all four dNTPs. Here we demonstrate that the phosphomimetic mutation T592E reduces the stability of the SAMHD1 tetramer and the dNTPase activity of the enzyme. To better understand the underlying mechanisms, we determined the crystal structures of SAMHD1 variants T592E and T592V. Although the neutral substitution T592V does not perturb the structure, the charged T592E induces large conformational changes, likely triggered by electrostatic repulsion from a distinct negatively charged environment surrounding Thr-592. The phosphomimetic mutation results in a significant decrease in the population of active SAMHD1 tetramers, and hence the dNTPase activity is substantially decreased. These results provide a mechanistic understanding of how SAMHD1 phosphorylation at residue Thr-592 may modulate its cellular and antiviral functions.

Monomeric GTP-Binding Proteins - chemistry

Humans

SAM Domain and HD Domain-Containing Protein 1

Enzyme Stability - genetics

Mutation, Missense

Substrate Specificity - genetics

Amino Acid Substitution

Details

Title: Subtitle: Impaired dNTPase activity of SAMHD1 by phosphomimetic mutation of Thr-592
Creators: Chenxiang Tang - From the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520 and
Xiaoyun Ji - From the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520 and
Li Wu - the Center for Retrovirus Research, Department of Veterinary Biosciences, Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio 43210
Yong Xiong - From the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520 and yong.xiong@yale.edu
Resource Type: Journal article
Publication Details: The Journal of biological chemistry, Vol.290(44), pp.26352-26359
DOI: 10.1074/jbc.m115.677435
PMID: 26294762
PMCID: PMC4646291
NLM abbreviation: J Biol Chem
ISSN: 1083-351X
eISSN: 1083-351X
Publisher: United States
Grant note: R01 AI102778 / NIAID NIH HHS R01 AI104483 / NIAID NIH HHS AI102778 / NIAID NIH HHS K99 AI120845 / NIAID NIH HHS AI104483 / NIAID NIH HHS AI120845 / NIAID NIH HHS
Language: English
Date published: 10/30/2015
Academic Unit: Microbiology and Immunology
Record Identifier: 9984001116502771

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