Expression and assembly of a fully active antibody in algae

Area of Science:

• Biotechnology
• Molecular Biology
• Algal Research

Background:

• Efficient production of complex recombinant proteins, such as antibodies, remains a challenge despite advances in antibody library technologies.
• The need for robust and scalable expression systems for therapeutic proteins is critical.

Purpose of the Study:

• To demonstrate the efficient expression of a unique large single-chain (lsc) antibody in the chloroplasts of Chlamydomonas reinhardtii.
• To optimize protein accumulation through codon bias and regulatory elements.
• To characterize the produced antibody and assess the potential of algae as a protein expression platform.

Main Methods:

• Synthesized a large single-chain (lsc) antibody gene with chloroplast codon bias.
• Utilized Chlamydomonas reinhardtii chloroplast promoters and 5' and 3' RNA elements for gene expression.
• Cultured the alga under specific growth regimes to modulate antibody accumulation.
• Analyzed antibody production, solubility, assembly, and post-translational modifications.

Main Results:

• Achieved high levels of soluble lsc antibody accumulation in Chlamydomonas reinhardtii chloroplasts.
• The expressed antibody, targeting herpes simplex virus glycoprotein D, assembled into higher-order complexes without significant post-translational modification.
• Antibody accumulation was successfully modulated by algal growth conditions and the choice of regulatory elements.
• Demonstrated the utility of algal chloroplasts as an effective expression system for recombinant proteins.

Conclusions:

• Chlamydomonas reinhardtii chloroplasts serve as a powerful platform for the high-level expression of complex recombinant proteins.
• A novel type of single-chain antibody, incorporating the entire heavy chain and Fc domain, was successfully produced.
• This work highlights the potential of algal biotechnology for producing therapeutic proteins efficiently.