Crystal structure of the AtTTM3 product complex with two orthophosphates and manganese ions (form B)

Experimental Data Snapshot

  • Resolution: 1.67 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 

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This is version 1.4 of the entry. See complete history


Structural Determinants for Substrate Binding and Catalysis in Triphosphate Tunnel Metalloenzymes.

Martinez, J.Truffault, V.Hothorn, M.

(2015) J Biol Chem 290: 23348

  • DOI: https://doi.org/10.1074/jbc.M115.674473
  • Primary Citation of Related Structures:  
    5A5Y, 5A60, 5A61, 5A64, 5A65, 5A66, 5A67, 5A68

  • PubMed Abstract: 

    Triphosphate tunnel metalloenzymes (TTMs) are present in all kingdoms of life and catalyze diverse enzymatic reactions such as mRNA capping, the cyclization of adenosine triphosphate, the hydrolysis of thiamine triphosphate, and the synthesis and breakdown of inorganic polyphosphates. TTMs have an unusual tunnel domain fold that harbors substrate- and metal co-factor binding sites. It is presently poorly understood how TTMs specifically sense different triphosphate-containing substrates and how catalysis occurs in the tunnel center. Here we describe substrate-bound structures of inorganic polyphosphatases from Arabidopsis and Escherichia coli, which reveal an unorthodox yet conserved mode of triphosphate and metal co-factor binding. We identify two metal binding sites in these enzymes, with one co-factor involved in substrate coordination and the other in catalysis. Structural comparisons with a substrate- and product-bound mammalian thiamine triphosphatase and with previously reported structures of mRNA capping enzymes, adenylate cyclases, and polyphosphate polymerases suggest that directionality of substrate binding defines TTM catalytic activity. Our work provides insight into the evolution and functional diversification of an ancient enzyme family.

  • Organizational Affiliation

    From the Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 1211 Geneva, Switzerland and.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
TRIPHOSPHATE TUNEL METALLOENZYME 3212Arabidopsis thalianaMutation(s): 0 
EC: (PDB Primary Data), (PDB Primary Data)
Find proteins for Q9SIY3 (Arabidopsis thaliana)
Explore Q9SIY3 
Go to UniProtKB:  Q9SIY3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9SIY3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.67 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 43.331α = 90
b = 33.811β = 94.4
c = 71.812γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-08-05
    Type: Initial release
  • Version 1.1: 2015-08-12
    Changes: Database references
  • Version 1.2: 2015-10-07
    Changes: Database references
  • Version 1.3: 2017-08-23
    Changes: Data collection
  • Version 1.4: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other