Affinity-Driven Site-Specific High Mannose Modification Determines the Structural Polymerization and Function of
Xiaoxue Yin1, Xiaoyu Li2,3, Liangliang Mu1
1School of Life Sciences, South China Normal University, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, Guangzhou, People's Republic of China.
Journal of Immunology (Baltimore, Md. : 1950)
|July 22, 2022
Summary
Teleost tetramer IgM
Area of Science:
- Immunology
- Glycobiology
- Structural Biology
Background:
- Teleost tetramer IgM is crucial for host defense against infection.
- Its structural diversity arises from variable disulfide polymerization.
- Previous studies showed teleost IgM H chains are N-glycan occupied.
Purpose of the Study:
- To investigate the functional roles of high-mannose modification in tilapia IgM.
- To understand the link between IgM structure, affinity, and function.
Main Methods:
- Mass spectrometry was used to analyze IgM structure and glycosylation.
- Immune response to trinitrophenyl (TNP) antigen was studied.
- Interaction between IgM, mannose receptor (MR), and phagocytes was examined.
Main Results:
- TNP-specific IgM affinity maturation occurred in tilapia.
- A positive correlation was found between IgM affinity and disulfide polymerization.
- High-mannose modification at Asn-509 site linked affinity and polymerization.
- Increased high mannose enhanced IgM-MR interaction and phagocytosis of Streptococcus agalactiae.
Conclusions:
- Site-specific high-mannose modification on IgM is associated with antibody affinity and structural polymerization.
- This modification enhances phagocyte function through interaction with the mannose receptor.
- Provides insights into IgM structure-function relationships during immune system evolution.
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