Crystal structure of the Fab fragment of therapeutic antibody Basiliximab in complex with IL-2Ra (CD25) ectodomainCrystal structure of the Fab fragment of therapeutic antibody Basiliximab in complex with IL-2Ra (CD25) ectodomain

Structural highlights

3iu3 is a 9 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.9Å
Ligands:,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Disease

IGKC_HUMAN Defects in IGKC are the cause of immunoglobulin kappa light chain deficiency (IGKCD) [MIM:614102. IGKCD is a disease characterized by the complete absence of immunoglobulin kappa chains.[1]

Function

IGKC_HUMAN

Evolutionary Conservation

 

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

IL-2 signaling plays a central role in the initiation and activation of immune responses. Correspondingly, blockage of this pathway leads to inhibition of the immune system and would provide some therapeutic benefits. Basiliximab (Simulect), a therapeutic mAb drug with specificity against IL-2R alpha of T cells, was approved by U.S. Food and Drug Administration in 1998. It has been proven to be effective in the suppression of the IL-2 pathway and hence has been widely used to prevent allograft rejection in organ transplantation, especially in kidney transplants. In this study, we report the crystal structure of the basiliximab Fab in complex with the ectodomain of IL-2R alpha at 2.9 A resolution. In the complex structure, the Fab interacts with IL-2R alpha with extensive hydrophobic and hydrophilic interactions, accounting for a high binding affinity of 0.14 nM. The Ag binding site of basiliximab consists of all six CDR loops that form a large binding interface with a central shallow hydrophobic groove surrounded by four hydrophilic patches. The discontinuous epitope is composed of several segments from the D1 domain and a minor segment from the D2 domain that overlap with most of the regions responsible for the interactions with IL-2. Thus, basiliximab binding can completely block the interactions of IL-2 with IL-2R alpha and hence inhibit the activation of the IL-2 signal pathway. The structural results also provide important implications for the development of improved and new IL-2R alpha-targeted mAb drugs.

Structural basis for the blockage of IL-2 signaling by therapeutic antibody basiliximab.,Du J, Yang H, Zhang D, Wang J, Guo H, Peng B, Guo Y, Ding J J Immunol. 2010 Feb 1;184(3):1361-8. Epub 2009 Dec 23. PMID:20032294[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

See Also

References

  1. Stavnezer-Nordgren J, Kekish O, Zegers BJ. Molecular defects in a human immunoglobulin kappa chain deficiency. Science. 1985 Oct 25;230(4724):458-61. PMID:3931219
  2. Du J, Yang H, Zhang D, Wang J, Guo H, Peng B, Guo Y, Ding J. Structural basis for the blockage of IL-2 signaling by therapeutic antibody basiliximab. J Immunol. 2010 Feb 1;184(3):1361-8. Epub 2009 Dec 23. PMID:20032294 doi:10.4049/jimmunol.0903178

3iu3, resolution 2.90Å

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