3Q8E

Crystal structure of Protective Antigen W346F (pH 8.5)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.098 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.194 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

pH effects on binding between the anthrax protective antigen and the host cellular receptor CMG2.

Rajapaksha, M.Lovell, S.Janowiak, B.E.Andra, K.K.Battaile, K.P.Bann, J.G.

(2012) Protein Sci. 21: 1467-1480

  • DOI: 10.1002/pro.2136
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The anthrax protective antigen (PA) binds to the host cellular receptor capillary morphogenesis protein 2 (CMG2) with high affinity. To gain a better understanding of how pH may affect binding to the receptor, we have investigated the kinetics of bin ...

    The anthrax protective antigen (PA) binds to the host cellular receptor capillary morphogenesis protein 2 (CMG2) with high affinity. To gain a better understanding of how pH may affect binding to the receptor, we have investigated the kinetics of binding as a function of pH to the full-length monomeric PA and to two variants: a 2-fluorohistidine-labeled PA (2-FHisPA), which is ∼1 pH unit more stable to variations in pH than WT, and an ∼1 pH unit less stable variant in which Trp346 in the domain 2β(3) -2β(4) loop is substituted with a Phe (W346F). We show using stopped-flow fluorescence that the binding rate increases as the pH is lowered for all proteins, with little influence on the rate of dissociation. In addition, we have crystallized PA and the two variants and examine the influence of pH on structure. In contrast to previous X-ray studies, the domain 2β(3) -2β(4) loop undergoes little change in structure from pH ∼8 to 5.5 for the WT protein, but for the 2-FHis labeled and W346F mutant there are changes in structure consistent with previous X-ray studies. In accord with pH stability studies, we find that the average B-factor values increase by ∼20-30% for all three proteins at low pH. Our results suggest that for the full-length PA, low pH increases the binding affinity, likely through a change in structure that favors a more "bound-like" conformation.


    Organizational Affiliation

    Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Protective antigen
A
735Bacillus anthracisMutation(s): 1 
Gene Names: pagA (pag)
Find proteins for P13423 (Bacillus anthracis)
Go to UniProtKB:  P13423
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.098 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.194 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 71.372α = 90.00
b = 93.601β = 90.00
c = 117.205γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement
PDB_EXTRACTdata extraction
SCALAdata scaling
MOSFLMdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-02-15
    Type: Initial release
  • Version 1.1: 2012-08-15
    Type: Database references
  • Version 1.2: 2012-10-03
    Type: Database references