3Q3G

Crystal Structure of A-domain in complex with antibody


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.7 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.211 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Stable Coordination of the Inhibitory Ca2+ Ion at the Metal Ion-Dependent Adhesion Site in Integrin CD11b/CD18 by an Antibody-Derived Ligand Aspartate: Implications for Integrin Regulation and Structure-Based Drug Design.

Mahalingam, B.Ajroud, K.Alonso, J.L.Anand, S.Adair, B.D.Horenstein, A.L.Malavasi, F.Xiong, J.P.Arnaout, M.A.

(2011) J.Immunol. 187: 6393-6401

  • DOI: 10.4049/jimmunol.1102394
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • A central feature of integrin interaction with physiologic ligands is the monodentate binding of a ligand carboxylate to a Mg(2+) ion hexacoordinated at the metal ion-dependent adhesion site (MIDAS) in the integrin A domain. This interaction stabiliz ...

    A central feature of integrin interaction with physiologic ligands is the monodentate binding of a ligand carboxylate to a Mg(2+) ion hexacoordinated at the metal ion-dependent adhesion site (MIDAS) in the integrin A domain. This interaction stabilizes the A domain in the high-affinity state, which is distinguished from the default low-affinity state by tertiary changes in the domain that culminate in cell adhesion. Small molecule ligand-mimetic integrin antagonists act as partial agonists, eliciting similar activating conformational changes in the A domain, which has contributed to paradoxical adhesion and increased patient mortality in large clinical trials. As with other ligand-mimetic integrin antagonists, the function-blocking mAb 107 binds MIDAS of integrin CD11b/CD18 A domain (CD11bA), but in contrast, it favors the inhibitory Ca(2+) ion over the Mg(2+) ion at MIDAS. We determined the crystal structures of the Fab fragment of mAb 107 complexed to the low- and high-affinity states of CD11bA. Favored binding of the Ca(2+) ion at MIDAS is caused by the unusual symmetric bidentate ligation of a Fab-derived ligand Asp to a heptacoordinated MIDAS Ca(2+) ion. Binding of the Fab fragment of mAb 107 to CD11bA did not trigger the activating tertiary changes in the domain or in the full-length integrin. These data show that the denticity of the ligand Asp/Glu can modify the divalent cation selectivity at MIDAS and hence integrin function. Stabilizing the Ca(2+) ion at MIDAS by bidentate ligation to a ligand Asp/Glu may provide one approach for designing pure integrin antagonists.


    Organizational Affiliation

    Structural Biology Program, Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Antibody Light Chain
C, A, F, J
220N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Antibody Heavy chain
D, B, H, K
224N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Integrin alpha-M
G, E, I, L
190Homo sapiensMutation(s): 0 
Gene Names: ITGAM (CD11B, CR3A)
Find proteins for P11215 (Homo sapiens)
Go to Gene View: ITGAM
Go to UniProtKB:  P11215
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

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D, H
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
CL
Query on CL

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E, G, J, K
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

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A, B, C, D, G, J, K
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

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E, G, I, L
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

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A, B, C, D, E, F, G, J, K, L
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
PEG
Query on PEG

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H
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.7 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.211 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 81.939α = 90.00
b = 157.218β = 90.00
c = 232.128γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
PHASERphasing
BUSTERrefinement
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-11-30
    Type: Initial release
  • Version 1.1: 2011-12-28
    Type: Database references