The schematic structures resulting from 3D domain switching of the variable region # 4VL (yellow) in the light chain # 4C214A (light and yellow gray) of an antibody. The 3D-DS of the antibody light chain includes the development of dimers (structures consisting of two similar subunits) and tetramers (structures made up of 2 dimers with 4 similar subunits). “Our research study offers the very first report on the atomic-level structure of the 3D-DS phenomenon in an antibody light chains variable region,” points out Hirota.
The size exemption chromatography of the antibody light chain # 4C214A exposed that the antibody exists as private monomers and four-subunit tetramers. To determine the area where tetramers are formed, the scientists partitioned the antibody light chain into the variable area (the pointer of the Y-shaped antibody) and the consistent region (the middle part of the Y-shaped antibody).
A Japanese research team has found how antibody light chains aggregate through 3D domain swapping. This research study exposes that tetrameric formations might affect protein aggregation, using new insights for drug advancement and antibody quality control. Credit: SciTechDaily.com
The novel insights into antibody aggregation are expected to open up new avenues for research and therapeutic applications.
Antibodies (immunoglobulins) are Y-shaped proteins that recognize and neutralize particular pathogens. Their capability to target particular particles or cells has made them promising candidates for future drug advancement. Their light chains– parts of the antibody that contribute to binding and acknowledging to specific antigens– misfold and aggregate, leading to amyloidosis, a condition that brings about issues and tissue dysfunction in the body.
In the context of drug development, antibody aggregation can compromise their capability to bind to antigens and reduce their therapeutic potential. Lack of in-depth structural details on its aggregation is one of the aspects preventing development in the field. As an outcome, continuous efforts intend to offer comprehensive reports on aggregate structures and their formation systems to advance antibody drug advancement.
New Research on Antibody Aggregation
In a study released today (December 8) in Nature Communications, a team of researchers from Japan, led by Shun Hirota from Nara Institute of Science and Technology (NAIST), has recently supplied brand-new insights into the structures formed during antibody aggregation through 3D domain switching (3D-DS), a procedure where a specific region of a protein is exchanged in between two or more particles of the same protein. The 3D-DS procedure has actually been observed in numerous proteins but not in antibody light chains up until the present study.
The schematic structures resulting from 3D domain swapping of the variable region # 4VL (yellow) in the light chain # 4C214A (yellow and light gray) of an antibody. The light chain of the antibody was discovered to preserve a balance between tetrameric and monomeric states. Credit: Shun Hirota and Takahiro Sakai
Ingenious Methods Reveal New Insights
The 3D-DS of the antibody light chain involves the formation of dimers (structures consisting of two identical subunits) and tetramers (structures composed of two dimers with four identical subunits). “Our research study supplies the first report on the atomic-level structure of the 3D-DS phenomenon in an antibody light chains variable area,” points out Hirota.
Analyzing the Light Chain Structures
The size exemption chromatography of the antibody light chain # 4C214A exposed that the antibody exists as individual monomers and four-subunit tetramers. To figure out the region where tetramers are formed, the researchers separated the antibody light chain into the variable region (the tip of the Y-shaped antibody) and the continuous area (the middle part of the Y-shaped antibody). They found that the variable region # 4VL can switch between tetrameric and monomeric states.
Ramifications for Antibody Flexibility and Aggregation
More analysis using X-ray crystallography and thermodynamic simulations revealed that tetramer formation is driven by hydrophobic interactions happening in between 2 3D-DS dimers.
Compared to monomers, the tetramers were found to have more rigid β-sheet structures, making them less flexible. The formation of the 3D-DS tetramer can assist prevent protein aggregation by reducing versatility, potentially preventing the formation of insoluble aggregates. On the other hand, 3D-DS might promote aggregation of antibodies.
Hirota concludes: “These findings not only clarify the domain-swapped structure of the antibody light chain but likewise add to managing antibody quality and advancing the advancement of future molecular recognition representatives and drugs.”
Referral: “Thermodynamic and structural Insights into Antibody Light Chain Tetramer Formation through 3D Domain Swapping” by Takahiro Sakai, Tsuyoshi Mashima, Naoya Kobayashi, Hideaki Ogata, Lian Duan, Ryo Fujiki, Kowit Hengphasatporn, Taizo Uda, Yasuteru Shigeta, Emi Hifumi and Shun Hirota, 8 December 2023, Nature Communications.DOI: 10.1038/ s41467-023-43443-4.