1G2O

CRYSTAL STRUCTURE OF PURINE NUCLEOSIDE PHOSPHORYLASE FROM MYCOBACTERIUM TUBERCULOSIS IN COMPLEX WITH A TRANSITION-STATE INHIBITOR


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.191 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structures of purine nucleoside phosphorylase from Mycobacterium tuberculosis in complexes with immucillin-H and its pieces.

Shi, W.Basso, L.A.Santos, D.S.Tyler, P.C.Furneaux, R.H.Blanchard, J.S.Almo, S.C.Schramm, V.L.

(2001) Biochemistry 40: 8204-8215

  • DOI: 10.1021/bi010585p
  • Primary Citation of Related Structures:  
    1I80, 1G2O

  • PubMed Abstract: 
  • A structural genomics comparison of purine nucleoside phosphorylases (PNPs) indicated that the enzyme encoded by Mycobacterium tuberculosis (TB-PNP) resembles the mammalian trimeric structure rather than the bacterial hexameric PNPs. The crystal stru ...

    A structural genomics comparison of purine nucleoside phosphorylases (PNPs) indicated that the enzyme encoded by Mycobacterium tuberculosis (TB-PNP) resembles the mammalian trimeric structure rather than the bacterial hexameric PNPs. The crystal structure of M. tuberculosis PNP in complex with the transition-state analogue immucillin-H (ImmH) and inorganic phosphate was solved at 1.75 A resolution and confirms the trimeric structure. Binding of the inhibitor occurs independently at the three catalytic sites, unlike mammalian PNPs which demonstrate negative cooperativity in ImmH binding. Reduced subunit interface contacts for TB-PNP, compared to the mammalian enzymes, correlate with the loss of the cooperative inhibitor binding. Mammalian and TB-PNPs both exhibit slow-onset inhibition and picomolar dissociation constants for ImmH. The structure supports a catalytic mechanism of reactant destabilization by neighboring group electrostatic interactions, transition-state stabilization, and leaving group activation. Despite an overall amino acid sequence identity of 33% between bovine and TB-PNPs and almost complete conservation in active site residues, one catalytic site difference suggests a strategy for the design of transition-state analogues with specificity for TB-PNP. The structure of TB-PNP was also solved to 2.0 A with 9-deazahypoxanthine (9dHX), iminoribitol (IR), and PO(4) to reconstruct the ImmH complex with its separate components. One subunit of the trimer has 9dHX, IR, and PO(4) bound, while the remaining two subunits contain only 9dHX. In the filled subunit, 9dHX retains the contacts found in the ImmH complex. However, the region of IR that corresponds to the oxocarbenium ion is translocated in the direction of the reaction coordinate, and the nucleophilic phosphate rotates away from the IR group. Loose packing of the pieces of ImmH in the catalytic site establishes that covalent connectivity in ImmH is required to achieve the tightly bound complex.


    Organizational Affiliation

    Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PURINE NUCLEOSIDE PHOSPHORYLASEA, B, C268Mycobacterium tuberculosisMutation(s): 0 
EC: 2.4.2.1
Find proteins for P9WP01 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WP01 
Go to UniProtKB:  P9WP01
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
IMH
Query on IMH

Download CCD File 
A, B, C
1,4-DIDEOXY-4-AZA-1-(S)-(9-DEAZAHYPOXANTHIN-9-YL)-D-RIBITOL
C11 H14 N4 O4
IWKXDMQDITUYRK-KUBHLMPHSA-N
 Ligand Interaction
PO4
Query on PO4

Download CCD File 
A, B, C
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
IMHKi:  0.02800000086426735   nM  Binding MOAD
IMHKi :  0.02800000086426735   nM  PDBBind
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.191 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 102.625α = 90
b = 102.625β = 90
c = 128.478γ = 120
Software Package:
Software NamePurpose
AMoREphasing
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-08-01
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance