The Retroviral Restriction Ability of SAMHD1, but Not Its Deoxynucleotide Triphosphohydrolase Activity, Is Regulated by Phosphorylation

Cell Host Microbe. 2013 Apr 17;13(4):441-51. doi: 10.1016/j.chom.2013.03.005.

Abstract

SAMHD1 is a cellular enzyme that depletes intracellular deoxynucleoside triphosphates (dNTPs) and inhibits the ability of retroviruses, notably HIV-1, to infect myeloid cells. Although SAMHD1 is expressed in both cycling and noncycling cells, the antiviral activity of SAMHD1 is limited to noncycling cells. We determined that SAMHD1 is phosphorylated on residue T592 in cycling cells but that this phosphorylation is lost when cells are in a noncycling state. Reverse genetic experiments revealed that SAMHD1 phosphorylated on residue T592 is unable to block retroviral infection, but this modification does not affect the ability of SAMHD1 to decrease cellular dNTP levels. SAMHD1 contains a target motif for cyclin-dependent kinase 1 (cdk1) ((592)TPQK(595)), and cdk1 activity is required for SAMHD1 phosphorylation. Collectively, these findings indicate that phosphorylation modulates the ability of SAMHD1 to block retroviral infection without affecting its ability to decrease cellular dNTP levels.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • CDC2 Protein Kinase / genetics
  • CDC2 Protein Kinase / metabolism
  • Cell Line
  • Cell Line, Tumor
  • HEK293 Cells
  • Humans
  • Monomeric GTP-Binding Proteins / genetics*
  • Monomeric GTP-Binding Proteins / metabolism*
  • Myeloid Cells / metabolism
  • Myeloid Cells / virology
  • Nucleotides / genetics
  • Nucleotides / metabolism
  • Phosphorylation
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Retroviridae / genetics*
  • Retroviridae / metabolism*
  • Retroviridae Infections / genetics*
  • Retroviridae Infections / metabolism*
  • Retroviridae Infections / virology
  • SAM Domain and HD Domain-Containing Protein 1
  • U937 Cells

Substances

  • Nucleotides
  • RNA-Binding Proteins
  • CDC2 Protein Kinase
  • SAM Domain and HD Domain-Containing Protein 1
  • SAMHD1 protein, human
  • Monomeric GTP-Binding Proteins