Structural insights into secretory immunoglobulin A and its interaction with a pneumococcal adhesin  

作　　者：Yuxin Wang Guopeng Wang Yaxin Li Qinyu Zhu Hao Shen Ning Gao Junyu Xiao 

机构地区：[1]State Key Laboratory of Protein and Plant Gene Research,Peking University,Beijing,100871,China [2]School of Life Sciences,Peking University,Beijing,100871,China [3]State Key Laboratory of Membrane Biology,Peking University,Beijing,100871,China [4]Peking-Tsinghua Center for Life Sciences,Peking University,Beijing,100871,China

出　　处：《Cell Research》2020年第7期602-609,共8页细胞研究（英文版）

基　　金：the National Center for Protein Sciences at Peking University for assistance with Amersham Imager;and Guilan Li for help with cDNA library.The work was supported by the National Key Research and Development Program of China(2017YFA0505200 and 2016YFC0906000 to J.X.;2019YFA0508904 to N.G.);the National Science Foundation of China(31570735 and 31822014 to J.X.;31725007 and 31630087 to N.G.);the Qidong-SLS Innovation Fund to J.X.and N.G.;and the Clinical Medicine Plus X Project of Peking University to J.X.

摘　　要：Secretory Immunoglobulin A(SIgA)is the most abundant antibody at the mucosal surface.It possesses two additional subunits besides IgA:the joining chain(J-chain)and secretory component(SC).SC is the ectodomain of the polymeric immunoglobulin receptor(pIgR),which functions to transport IgA to the mucosa.How the J-chain and pIgR/SC facilitate the assembly and secretion of SIgA remains incompletely understood.Furthermore,during the infection of Streptococcus pneumoniae,the pneumococcal adhesin SpsA hijacks pIgR/SC and SIgA to gain entry to human cells and evade host defense.How SpsA targets pIgR/SC and SIgA also remains elusive.Here we report a cryo-electron microscopy structure of the Fc region of IgA1(Fcα)in complex with the J-chain and SC(Fcα-J-SC),which reveals the organization principle of SIgA.We also present a structure of Fcα-J-SC complexed with SpsA,which uncovers the specific interactions between SpsA and human pIgR/SC.These results advance the molecular understanding of SIgA and shed light on S.pneumoniae pathogenesis.

关 键 词：SIGA INTERACTION INCOMPLETE 

分 类 号：Q24[生物学—细胞生物学]