Yeast display platform successfully presents single-chain Fc fragments with tailored effector molecule binding

Antibody engineering is crucial for developing novel therapeutics, with Fc fragments playing a key role in effector functions and half-life. Traditional antibody formats can be limited in their ability to precisely position binding sites for multispecific molecules. The single-chain Fc (scFc) format offers unique opportunities for novel molecular architectures but requires specialized design, particularly concerning linkers. Optimizing Fc fragment properties, such as binding specificity and affinity to Fc gamma receptors (FcγRs), is vital for enhancing therapeutic efficacy and reducing off-target effects. Yeast display is a powerful tool for directed evolution and optimization of protein properties, including antibody fragments, by presenting thousands of variants on the cell surface for high-throughput screening.

Researchers investigated the suitability of a yeast display system for presenting single-chain IgG Fc fragments. They designed and constructed single-chain Fc molecules, paying particular attention to linker design, which is critical for this format's unique features. The yeast system was then used to express these scFc fragments on the surface of Saccharomyces cerevisiae. Following display, the expressed fragments were characterized for their binding capabilities. Specifically, the study assessed the binding of the displayed scFc fragments to various structural markers and, importantly, to Fc gamma receptors. This characterization aimed to confirm efficient presentation and evaluate the modulated binding properties of the engineered scFc fragments, setting the stage for future directed evolution efforts.

The study successfully demonstrated the amenability of the yeast display system for the efficient presentation of single-chain IgG Fc fragments. This platform enabled the display of scFc variants on the yeast surface, confirming their structural integrity and accessibility for ligand interaction. Researchers characterized the displayed fragments, observing their binding to relevant structural markers, which validated proper folding and surface expression. Crucially, the engineered scFc fragments exhibited modulated binding to Fc gamma receptors, indicating that the single-chain format, when properly designed, can retain and even tailor its interaction with key effector molecules. This finding suggests that the unique features of the single-chain Fc, such as its linker, can be effectively managed within the yeast display context to achieve desired binding profiles. The successful presentation and characterization lay a robust foundation for future directed evolution.

The yeast display system proved effective for presenting single-chain IgG Fc fragments, allowing for the characterization of their binding to structural markers and Fc gamma receptors.