6C5I

Unliganded S25-5 Fab


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.89 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.193 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Subtle Changes in the Combining Site of the Chlamydiaceae-Specific mAb S25-23 Increase the Antibody-Carbohydrate Binding Affinity by an Order of Magnitude.

Haji-Ghassemi, O.Muller-Loennies, S.Brooks, C.L.MacKenzie, C.R.Caveney, N.Van Petegem, F.Brade, L.Kosma, P.Brade, H.Evans, S.V.

(2019) Biochemistry 58: 714-726

  • DOI: 10.1021/acs.biochem.8b00318
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Murine antibodies S25-23, S25-26, and S25-5 derive from a common germ-line origin, and all bind the Chlamydiaceae family-specific epitope αKdo(2→8)αKdo(2→4)αKdo (where Kdo is 3-deoxy-α-d- manno-oct-2-ulosonic acid) with high affinity and specificity. ...

    Murine antibodies S25-23, S25-26, and S25-5 derive from a common germ-line origin, and all bind the Chlamydiaceae family-specific epitope αKdo(2→8)αKdo(2→4)αKdo (where Kdo is 3-deoxy-α-d- manno-oct-2-ulosonic acid) with high affinity and specificity. These antibodies recognize the entire trisaccharide antigen in a linkage-dependent manner via a groove composed largely of germ-line residues. Despite sharing identical heavy and light chain genes, S25-23 binds the family-specific epitope with nanomolar affinity, which is an order of magnitude higher than that of S25-26, while S25-5 displays an affinity between those of S25-23 and S25-26. We determined the high-resolution crystal structures of S25-23 and S25-5 antigen binding fragments in complex with a pentasaccharide derived from the LPS of Chlamydia and measured the affinity of S25-5 for chlamydial LPS antigens using isothermal titration microcalorimetry. The 1.75 Å resolution structure of S25-23 shows how subtle conservative mutations Arg(L)-27E to lysine and Ser(H)-56 to threonine lead to an order of magnitude increase in affinity. Importantly, comparison between previous S25-26 structures and the 1.99 and 2.05 Å resolution liganded and unliganded structures of S25-5, respectively, shows how a Ser(L)-27E mutation results in an intermediate affinity due to the reduced enthalpic penalty associated with complex formation that would otherwise be required for arginine in this position. This strategy allows for subtle adjustments in the combining site via affinity maturation that have dramatic consequences for the affinity of an antibody for its antigen.


    Organizational Affiliation

    Research Center Borstel , Leibniz Lung Center , Parkallee 22 , Borstel D-23845 , Germany.,Human Health Therapeutics Portfolio , National Research Council Canada , 100 Sussex Drive , Ottawa , Ontario , Canada K1A 0R6.,Department of Chemistry , Fresno State University , 2555 East San Ramon Avenue, MS SB70 , Fresno , California 93740 , United States.,Department of Chemistry , University of Natural Resources and Life Sciences , A-1190 Vienna , Austria.,Department of Biochemistry and Microbiology , University of Victoria , P.O. Box 3055 STN CSC, Victoria , British Columbia , Canada V8P 3P6.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Fab IgG1 Heavy Chain
H
218Mus musculusMutation(s): 0 
Gene Names: Igh
Find proteins for Q99LC4 (Mus musculus)
Go to UniProtKB:  Q99LC4
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Fab IgG1 (kappa) Light Chain
L
219N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CL
Query on CL

Download SDF File 
Download CCD File 
H
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
PG0
Query on PG0

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Download CCD File 
L
2-(2-METHOXYETHOXY)ETHANOL
PEG 6000
C5 H12 O3
SBASXUCJHJRPEV-UHFFFAOYSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
H
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
NI
Query on NI

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Download CCD File 
L
NICKEL (II) ION
Ni
VEQPNABPJHWNSG-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.89 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.193 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 64.635α = 90.00
b = 72.877β = 90.00
c = 109.015γ = 90.00
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
REFMACrefinement
SCALEPACKdata scaling
PHASERphasing
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Natural Sciences and Engineering Research Council (Canada)CanadaDiscovery Grant 171356-2013

Revision History 

  • Version 1.0: 2019-01-09
    Type: Initial release
  • Version 1.1: 2019-02-27
    Type: Data collection, Database references