8GHZ

Cryo-EM structure of fish immunogloblin M-Fc

Summary for 8GHZ

• Entry DOI: 10.2210/pdb8ghz/pdb
• EMDB information: 40054
• Descriptor: Teleost immunoglobulin M protein, beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose (2 entities in total)
• Functional Keywords: immunoglobulin m, igm, immune system
• Biological source: Oncorhynchus mykiss (rainbow trout)
• Total number of polymer chains: 8
• Total formula weight: 220680.45

Authors

Lyu, M.,Stadtmueller, B.M.,Malyutin, A.G. (deposition date: 2023-03-13, release date: 2023-11-08, Last modification date: 2024-03-27)

Primary citation

Lyu, M.,Malyutin, A.G.,Stadtmueller, B.M.
The structure of the teleost Immunoglobulin M core provides insights on polymeric antibody evolution, assembly, and function.
Nat Commun, 14:7583-7583, 2023

PubMed Abstract: Polymeric (p) immunoglobulins (Igs) serve broad functions during vertebrate immune responses. Typically, pIgs contain between two and six Ig monomers, each with two antigen binding fragments and one fragment crystallization (Fc). In addition, many pIgs assemble with a joining-chain (JC); however, the number of monomers and potential to include JC vary with species and heavy chain class. Here, we report the cryo-electron microscopy structure of IgM from a teleost (t) species, which does not encode JC. The structure reveals four tIgM Fcs linked through eight C-terminal tailpieces (Tps), which adopt a single β-sandwich-like domain (Tp assembly) located between two Fcs. Specifically, two of eight heavy chains fold uniquely, resulting in a structure distinct from mammalian IgM, which typically contains five IgM monomers, one JC and a centrally-located Tp assembly. Together with mutational analysis, structural data indicate that pIgs have evolved a range of assembly mechanisms and structures, each likely to support unique antibody effector functions.

PubMed: 37989996
DOI: 10.1038/s41467-023-43240-z

Experimental method

ELECTRON MICROSCOPY (2.78 Å)