1LLN

1.6A CRYSTAL STRUCTURE OF POKEWEED ANTIVIRAL PROTEIN-III (PAP-III) WITH METHYLATED LYSINES


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.201 
  • R-Value Observed: 0.203 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

High resolution X-ray structure of potent anti-HIV pokeweed antiviral protein-III

Kurinov, I.V.Uckun, F.M.

(2003) Biochem Pharmacol 65: 1709-1717

  • DOI: 10.1016/s0006-2952(03)00144-8
  • Primary Citation of Related Structures:  
    1LLN

  • PubMed Abstract: 
  • Pokeweed antiviral protein III (PAP-III), a naturally occurring protein isolated from late summer leaves of the pokeweed plant (Phytolacca americana), has potent anti-HIV activity by an as yet undetermined molecular mechanism. PAP-III belongs to a family ...

    Pokeweed antiviral protein III (PAP-III), a naturally occurring protein isolated from late summer leaves of the pokeweed plant (Phytolacca americana), has potent anti-HIV activity by an as yet undetermined molecular mechanism. PAP-III belongs to a family of ribosome-inactivating proteins that catalytically deadenylate ribosomal and viral RNA. The chemical modification of PAP-III by reductive methylation of its lysine residues significantly improved the crystal quality for X-ray diffraction studies. Trigonal crystals of the modified PAP-III, with unit cell parameters a=b=80.47A, c=76.21A, were obtained using 30% PEG400 as the precipitant. These crystals contained one enzyme molecule per asymmetric unit and diffracted up to 1.5A, when exposed to a synchrotron source. Here we report the X-ray crystal structure of PAP-III at 1.6A resolution, which was solved by molecular replacement using the homology model of PAP-III as a search model. The fold typical of other ribosome-inactivating proteins is conserved, despite several differences on the surface and in the loop regions. Residues Tyr(69), Tyr(117), Glu(172), and Arg(175) are expected to define the active site of PAP-III. Molecular modeling studies of the interactions of PAP-III and PAP-I with a single-stranded RNA heptamer predicted a more potent anti-HIV activity for PAP-III due to its unique surface topology and more favorable charge distribution in its 20A-long RNA binding active center cleft. In accordance with the predictions of the modeling studies, PAP-III was more potent than PAP-I in depurinating HIV-1 RNA.


    Related Citations: 
    • X-Ray Crystallographic Analysis of the Structural Basis for the Interactions of Pokeweed Antiviral Protein with its Active Site Inhibitor and Ribosomal RNA Substrate Analogs
      Kurinov, I.V., Myers, D.E., Irvin, J.D., Uckun, F.M.
      (1999) Protein Sci 8: 1765

    Organizational Affiliation

    The Biotherapy and Drug Discovery Program, Parker Hughes Cancer Center, 2699 Patton Road, St. Paul, MN 55113, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Antiviral Protein 3 A262Phytolacca americanaMutation(s): 14 
Gene Names: PAP2PAPII
EC: 3.2.2.22
Find proteins for Q40772 (Phytolacca americana)
Explore Q40772 
Go to UniProtKB:  Q40772
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MLY
Query on MLY
AL-PEPTIDE LINKINGC8 H18 N2 O2LYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.201 
  • R-Value Observed: 0.203 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 80.47α = 90
b = 80.47β = 90
c = 76.21γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-06-17
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance