ジャーナル: Nat Commun / 年: 2017 タイトル: Molecular basis of human CD22 function and therapeutic targeting. 著者: June Ereño-Orbea / Taylor Sicard / Hong Cui / Mohammad T Mazhab-Jafari / Samir Benlekbir / Alba Guarné / John L Rubinstein / Jean-Philippe Julien / 要旨: CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As a B-cell-restricted antigen, CD22 is targeted in therapies against dysregulated B cells that cause ...CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As a B-cell-restricted antigen, CD22 is targeted in therapies against dysregulated B cells that cause autoimmune diseases and blood cancers. Here we report the crystal structure of human CD22 at 2.1 Å resolution, which reveals that specificity for α2-6 sialic acid ligands is dictated by a pre-formed β-hairpin as a unique mode of recognition across sialic acid-binding immunoglobulin-type lectins. The CD22 ectodomain adopts an extended conformation that facilitates concomitant CD22 nanocluster formation on B cells and binding to trans ligands to avert autoimmunity in mammals. We structurally delineate the CD22 site targeted by the therapeutic antibody epratuzumab at 3.1 Å resolution and determine a critical role for CD22 N-linked glycosylation in antibody engagement. Our studies provide molecular insights into mechanisms governing B-cell inhibition and valuable clues for the design of immune modulators in B-cell dysfunction.The B-cell-specific co-receptor CD22 is a therapeutic target for depleting dysregulated B cells. Here the authors structurally characterize the ectodomain of CD22 and present its crystal structure with the bound therapeutic antibody epratuzumab, which gives insights into the mechanism of inhibition of B-cell activation.
構造決定の手法: 分子置換 開始モデル: Crystal structure from a different crystal obtained with this construct by MAD phasing with heavy atom 解像度: 2.12→46.242 Å / SU ML: 0.27 / 交差検証法: FREE R-VALUE / σ(F): 1.34 / 位相誤差: 25.99 / 立体化学のターゲット値: ML
Rfactor
反射数
%反射
Rfree
0.2321
940
5.02 %
Rwork
0.2021
-
-
obs
0.2037
18725
99.85 %
溶媒の処理
減衰半径: 0.9 Å / VDWプローブ半径: 1.11 Å / 溶媒モデル: FLAT BULK SOLVENT MODEL