2i26
From Proteopedia
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Crystal structure analysis of the nurse shark new antigen receptor ancestral variable domain in complex with lysozyme
Overview
Sharks express an unusual heavy-chain isotype called IgNAR, whose variable regions bind antigen as independent soluble domains. To further probe affinity maturation of the IgNAR response, we structurally characterized the germline and somatically matured versions of a type II variable (V) region, both in the presence and absence of its antigen, hen egg-white lysozyme. Despite a disulfide bond linking complementarity determining regions (CDRs) 1 and 3, both germline and somatically matured V regions displayed significant structural changes in these CDRs upon complex formation with antigen. Somatic mutations in the IgNAR V region serve to increase the number of contacts with antigen, as reflected by a tenfold increase in affinity, and one of these mutations appears to stabilize the CDR3 region. In addition, a residue in the HV4 loop plays an important role in antibody-antigen interaction, consistent with the high rate of somatic mutations in this non-CDR loop.
About this Structure
2I26 is a Single protein structure of sequence from Gallus gallus and Ginglymostoma cirratum with as ligand. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Maturation of shark single-domain (IgNAR) antibodies: evidence for induced-fit binding., Stanfield RL, Dooley H, Verdino P, Flajnik MF, Wilson IA, J Mol Biol. 2007 Mar 23;367(2):358-72. Epub 2006 Dec 22. PMID:17258766
Page seeded by OCA on Thu Feb 21 17:48:21 2008
