Format

Send to

Choose Destination
See comment in PubMed Commons below
PLoS Pathog. 2015 Oct 2;11(10):e1005194. doi: 10.1371/journal.ppat.1005194. eCollection 2015.

Phospho-dependent Regulation of SAMHD1 Oligomerisation Couples Catalysis and Restriction.

Author information

1
The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, United Kingdom.
2
The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, United Kingdom; Faculty of Medicine, Imperial College London, London, United Kingdom.
3
Centre for Genomic Medicine, Institute for Human Development, Faculty of Medicine and Human Sciences, University of Manchester, Manchester, United Kingdom.

Abstract

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 and virological data demonstrating that in addition to allosteric activation and triphosphohydrolase activity, restriction correlates with the capacity of SAMHD1 to form "long-lived" enzymatically competent tetramers. Tetramer disruption invariably abolishes restriction but has varied effects on in vitro triphosphohydrolase activity. SAMHD1 phosphorylation also ablates restriction and tetramer formation but without affecting triphosphohydrolase steady-state kinetics. However phospho-SAMHD1 is unable to catalyse dNTP turnover under conditions of nucleotide depletion. Based on our findings we propose a model for phosphorylation-dependent regulation of SAMHD1 activity where dephosphorylation switches housekeeping SAMHD1 found in cycling cells to a high-activity stable tetrameric form that depletes and maintains low levels of dNTPs in differentiated cells.

PMID:
26431200
PMCID:
PMC4592219
DOI:
10.1371/journal.ppat.1005194
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Public Library of Science Icon for PubMed Central
    Loading ...
    Support Center