Bos taurus ultralong CDR H3 antibodies

Area of Science:

• Immunology
• Molecular Biology
• Structural Biology

Background:

• Antibodies are crucial for immune defense.
• Antibody diversity is generated through genetic recombination and somatic hypermutation.
• The third complementarity determining region of the heavy chain (CDR H3) is a key determinant of antigen-binding specificity.

Purpose of the Study:

• To investigate the unique structural and diversity-generating features of cow antibodies.
• To understand the role of the long CDR H3 in the cow antibody system.

Main Methods:

• Bioinformatic analysis of antibody sequences.
• Structural analysis of CDR H3 domains.
• Investigation of somatic hypermutation processes in B cells.

Main Results:

• Cow antibodies exhibit exceptionally long CDR H3 regions forming a distinct disulfide-bonded 'knob' domain atop a β-ribbon 'stalk'.
• Somatic hypermutation of a single VDJ rearrangement generates extensive sequence and disulfide bonding diversity within the CDR H3 knob.
• This mechanism provides a unique scaffold for antigen binding and an unusual diversity-creating process.

Conclusions:

• Cow antibody system represents a unique evolutionary adaptation among vertebrates.
• The distinct CDR H3 structure and diversity generation mechanism offer novel insights into antibody function and evolution.