1osx
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Solution Structure of the Extracellular Domain of BLyS Receptor 3 (BR3)
OverviewOverview
BAFF/BLyS, a member of the tumor necrosis family (TNF) superfamily of, ligands, is a crucial survival factor for B cells. BAFF binds three, receptors, TACI, BCMA, and BR3, with signaling through BR3 being essential, for promoting B cell function. Typical TNF receptor (TNFR) family members, bind their cognate ligands through interactions with two cysteine-rich, domains (CRDs). However, the extracellular domain (ECD) of BR3 consists of, only a partial CRD, with cysteine spacing distinct from other modules, described previously. Herein, we report the solution structure of the BR3, ECD. A core region of only 19 residues adopts a stable structure in, solution. The BR3 fold is analogous to the first half of a canonical TNFR, CRD but is stabilized by an additional noncanonical disulfide bond., BAFF-binding determinants were identified by shotgun alanine-scanning, mutagenesis of the BR3 ECD expressed on phage. Several of the key, BAFF-binding residues are presented from a beta-turn that we have shown, previously to be sufficient for ligand binding when transferred to a, structured beta-hairpin scaffold [Kayagaki, N., Yan, M., Seshasayee, D., Wang, H., Lee, W., French, D. M., Grewal, I. S., Cochran, A. G., Gordon, N. C., Yin, J., Starovasnik, M. A, and Dixit, V. M. (2002) Immunity 10, 515-524]. Outside of the turn, mutagenesis identifies additional, hydrophobic contacts that enhance the BAFF-BR3 interaction. The crystal, structure of the minimal hairpin peptide, bhpBR3, in complex with BAFF, reveals intimate packing of the six-residue BR3 turn into a cavity on the, ligand surface. Thus, BR3 binds BAFF through a highly focused interaction, site, unprecedented in the TNFR family.
About this StructureAbout this Structure
1OSX is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
BAFF/BLyS receptor 3 comprises a minimal TNF receptor-like module that encodes a highly focused ligand-binding site., Gordon NC, Pan B, Hymowitz SG, Yin J, Kelley RF, Cochran AG, Yan M, Dixit VM, Fairbrother WJ, Starovasnik MA, Biochemistry. 2003 May 27;42(20):5977-83. PMID:12755599
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