Display of heterologous proteins on the surface of microorganisms: from the screening of combinatorial libraries to live recombinant vaccines

Yeast surface display for screening combinatorial polypeptide libraries

Display on the yeast cell wall is well suited for engineering mammalian cell-surface and secreted proteins (e.g., antibodies, receptors, cytokines) that require endoplasmic reticulum-specific post-translational processing for efficient folding and activity. C-terminal fusion to the Aga2p mating adhesion receptor of Saccharomyces cerevisiae has been used for the selection of scFv antibody fragments with threefold decreased antigen dissociation rate from a randomly mutated library. A eukaryotic host should alleviate expression biases present in bacterially propagated combinatorial libraries. Quantitative flow cytometric analysis enables fine discrimination of kinetic parameters for protein binding to soluble ligands.

Engineered cell surfaces: fertile ground for molecular landscaping

The cell surface contains a wealth of information that determines how cells interact with their environment. Methods for directing the cell surface expression of novel protein-based and oligosaccharide-based epitopes are stimulating new directions in biotechnology and biomedical research.

Bacterial surface display: trends and progress

Heterologous surface display on Gram-negative bacterial was first described a decade ago and is now an active research area. More recently, strategies for surface display on Gram-positive bacterial have also been devised and these carry some inherent advantages. Bacterial surface display has found a range of applications in the expression of various antigenic determinants, heterologous enzymes, single-chain antibodies, polyhistidyl tags and even entire peptide libraries. This article explains the basis of bacterial surface display and discusses current uses and possible future trends of this emerging technology.