On-Membrane Dynamic Interplay between Anti-GM1 IgG Antibodies and Complement Component C1q.
Int J Mol Sci
; 21(1)2019 Dec 24.
Article
en En
| MEDLINE
| ID: mdl-31878295
ABSTRACT
Guillain-Barré syndrome, an autoimmune neuropathy characterized by acute limb weakness, is often preceded by Campylobacter jejuni infection. Molecular mimicry exists between the bacterial lipo-oligosaccharide and human ganglioside. Such C. jejuni infection induces production of immunoglobulin G1 (IgG1) autoantibodies against GM1 and causes complement-mediated motor nerve injury. For elucidating the molecular mechanisms linking autoantigen recognition and complement activation, we characterized the dynamic interactions of anti-GM1 IgG autoantibodies on ganglioside-incorporated membranes. Using high-speed atomic force microscopy, we found that the IgG molecules assemble into a hexameric ring structure on the membranes depending on their specific interactions with GM1. Complement component C1q was specifically recruited onto these IgG rings. The ring formation was inhibited by an IgG-binding domain of staphylococcal protein A bound at the cleft between the CH2 and CH3 domains. These data indicate that the IgG assembly is mediated through Fc-Fc interactions, which are promoted under on-membrane conditions due to restricted translational diffusion of IgG molecules. Reduction and alkylation of the hinge disulfide impaired IgG ring formation, presumably because of an increase in conformational entropic penalty. Our findings provide mechanistic insights into the molecular processes involved in Guillain-Barré syndrome and, more generally, into antigen-dependent interplay between antibodies and complement components on membranes.
Palabras clave
Texto completo:
1
Base de datos:
MEDLINE
Asunto principal:
Inmunoglobulina G
/
Complemento C1q
/
Gangliósido G(M1)
Límite:
Humans
Idioma:
En
Revista:
Int J Mol Sci
Año:
2019
Tipo del documento:
Article
País de afiliación:
Japón