3QA3

Crystal Structure of A-domain in complex with antibody


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 

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:  
    3QA3, 3Q3G

  • 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 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 ...

    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
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Antibody Light chainD [auth A], A [auth C], G [auth F], J220Mus musculusMutation(s): 0 
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Antibody Heavy chainE [auth B], B [auth D], H, K224Mus musculusMutation(s): 0 
Protein Feature View
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Integrin alpha-MF [auth E], C [auth G], I, L190Homo sapiensMutation(s): 1 
Gene Names: ITGAMCD11BCR3A
UniProt & NIH Common Fund Data Resources
Find proteins for P11215 (Homo sapiens)
Explore P11215 
Go to UniProtKB:  P11215
PHAROS:  P11215
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download Ideal Coordinates CCD File 
O [auth D], S [auth G], T [auth G], U [auth A], V [auth B]GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

Download Ideal Coordinates CCD File 
AA [auth J], BA [auth K], M [auth C], N [auth C], P [auth D], Q [auth D], X [auth H], Z [auth J]1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

Download Ideal Coordinates CCD File 
CA [auth L], R [auth G], W [auth E], Y [auth I]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 82.604α = 90
b = 158.346β = 90
c = 233.319γ = 90
Software Package:
Software NamePurpose
BUSTERrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

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