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 

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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: 10.1107/S1399004714027527
  • Primary Citation of Related Structures:  
    4RXR, 4RXS, 4RXO, 4RXP, 4RXQ

  • 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 ...

    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
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Deoxynucleoside triphosphate triphosphohydrolase SAMHD1A, B539Homo 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
Protein Feature View
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  • Reference Sequence
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