4RXS

The structure of GTP-dTTP-bound SAMHD1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.195 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.2 of the entry. See complete history


Literature

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

Zhu, C.F.Wei, W.Peng, X.Dong, Y.H.Gong, Y.Yu, X.F.

(2015) Acta Crystallogr D Biol Crystallogr 71: 516-524

  • DOI: https://doi.org/10.1107/S1399004714027527
  • Primary Citation of Related Structures:  
    4RXO, 4RXP, 4RXQ, 4RXR, 4RXS

  • PubMed Abstract: 

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


  • Organizational Affiliation

    School of Life Sciences, Tianjin University, Tianjin, People's Republic of China.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Deoxynucleoside triphosphate triphosphohydrolase SAMHD1
A, B
539Homo sapiensMutation(s): 0 
Gene Names: SAMHD1MOP5
EC: 3.1.5
UniProt & NIH Common Fund Data Resources
Find proteins for Q9Y3Z3 (Homo sapiens)
Explore Q9Y3Z3 
Go to UniProtKB:  Q9Y3Z3
PHAROS:  Q9Y3Z3
GTEx:  ENSG00000101347 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9Y3Z3
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
GTP
Query on GTP

Download Ideal Coordinates CCD File 
C [auth A],
F [auth A]
GUANOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O14 P3
XKMLYUALXHKNFT-UUOKFMHZSA-N
TTP
Query on TTP

Download Ideal Coordinates CCD File 
D [auth A],
E [auth A],
I [auth B],
J [auth B]
THYMIDINE-5'-TRIPHOSPHATE
C10 H17 N2 O14 P3
NHVNXKFIZYSCEB-XLPZGREQSA-N
MG
Query on MG

Download Ideal Coordinates CCD File 
G [auth A],
H [auth B]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.195 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 151.686α = 90
b = 109.757β = 122.8
c = 92.951γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASESphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-03-11
    Type: Initial release
  • Version 1.1: 2015-03-25
    Changes: Database references
  • Version 1.2: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description