1YFZ

Novel IMP Binding in Feedback Inhibition of Hypoxanthine-Guanine Phosphoribosyltransferase from Thermoanaerobacter tengcongensis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.219 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Alternative IMP Binding in Feedback Inhibition of Hypoxanthine-Guanine Phosphoribosyltransferase from Thermoanaerobacter tengcongensis.

Chen, Q.Liang, Y.Su, X.Gu, X.Zheng, X.Luo, M.

(2005) J.Mol.Biol. 348: 1199-1210

  • DOI: 10.1016/j.jmb.2005.02.064

  • PubMed Abstract: 
  • Crystal structures of Thermoanaerobacter tengcongensis hypoxanthine-guanine phosphoribosyltransferase (HGPRT) apoenzyme and the enzyme-inosine monophosphate (IMP) complex have been determined to 2.5A and 2.2A resolution, respectively. The active form ...

    Crystal structures of Thermoanaerobacter tengcongensis hypoxanthine-guanine phosphoribosyltransferase (HGPRT) apoenzyme and the enzyme-inosine monophosphate (IMP) complex have been determined to 2.5A and 2.2A resolution, respectively. The active form of the enzyme was identified as a tetramer in solution and the K(i) value of IMP was measured to be 45 microM for alpha-D-phosphoribosyl-1-pyrophosphate (PRPP). Conformation of the flexible loop in T.tengcongensis HGPRT, which is involved in substrate PRPP binding, is different from that observed in phosphoribosyltransferases (PRTs). It contains a 3-10 helix, and a unique double serine repeat. This loop is ordered even in the apoenzyme and assumes a half-closed conformation. The primary magnesium ion is directly coordinated by side-chains of Glu101 and Asp102, and water molecules in the apoenzyme, suggesting a possible prerequisite role for substrate PRPP binding. Most interestingly, an alternative IMP binding mode is found in the structure of T.tengcongensis HGPRT-IMP complex. The 5'-phosphate of IMP occupies the PPi position usually seen in PRT-PRPP complexes. This new observation is consistent with the lower K(i) value of IMP and may suggest a mechanism involving multiple modes of interactions between IMP and T.tengcongensis HGPRT in product release and feedback inhibition. The structure of T.tengcongensis HGPRT is compared with those of mesophilic HPRTs, and several possible features contributing to its thermostability are elucidated. Overall, T.tengcongensis HGPRT appears to be more diverged from other PRTs.


    Organizational Affiliation

    Laboratory of Structural Biology, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Hypoxanthine-guanine phosphoribosyltransferase
A, B
205Caldanaerobacter subterraneus subsp. tengcongensis (strain DSM 15242 / JCM 11007 / NBRC 100824 / MB4)Gene Names: Hpt
Find proteins for Q8R7L0 (Caldanaerobacter subterraneus subsp. tengcongensis (strain DSM 15242 / JCM 11007 / NBRC 100824 / MB4))
Go to UniProtKB:  Q8R7L0
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
IMP
Query on IMP

Download SDF File 
Download CCD File 
A, B
INOSINIC ACID
C10 H13 N4 O8 P
GRSZFWQUAKGDAV-KQYNXXCUSA-N
 Ligand Interaction
ACT
Query on ACT

Download SDF File 
Download CCD File 
A, B
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
IMPKi: 45000 nM BINDINGMOAD
IMPKi: 45000 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.219 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 65.770α = 90.00
b = 137.730β = 90.00
c = 95.270γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
PROTEUM PLUSdata reduction
CNSphasing
PROTEUM PLUSdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-05-10
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Source and taxonomy, Version format compliance
  • Version 1.3: 2011-11-16
    Type: Atomic model