Rescue and In Situ Selection and Evaluation (RISE): A Method for High-Throughput Panning of Phage Display Libraries

Phage display and other peptide display technologies

Phage display technology, which is based on the presentation of peptide sequences on the surface of bacteriophage virions, was developed over 30 years ago. Improvements in phage display systems have allowed us to employ this method in numerous fields of biotechnology, as diverse as immunological and biomedical applications, the formation of novel materials and many others. The importance of phage display platforms was recognized by awarding the Nobel Prize in 2018 "for the phage display of peptides and antibodies". In contrast to many review articles concerning specific applications of phage display systems published in recent years, we present an overview of this technology, including a comparison of various display systems, their advantages and disadvantages, and examples of applications in various fields of science, medicine, and the broad sense of biotechnology. Other peptide display technologies, which employ bacterial, yeast and mammalian cells, as well as eukaryotic viruses and cell-free systems, are also discussed. These powerful methods are still being developed and improved; thus, novel sophisticated tools based on phage display and other peptide display systems are constantly emerging, and new opportunities to solve various scientific, medical and technological problems can be expected to become available in the near future.

Class III peroxidases are activated in proanthocyanidin-deficient Arabidopsis thaliana seeds

BACKGROUND AND AIMS

It has previously been shown that proanthocyanidins (PAs) in the seed coat of Arabidopsis thaliana have the ability to scavenge superoxide radicals (O2(-)). However, the physiological processess in PA-deficit seeds are not clear. It is hypothesized that there exist alternative ways in PA-deficient seeds to cope with oxidative stress.

METHODS

The content of hydrogen peroxide (H2O2) and its relevance to the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidases was investigated in both wild-type and PA-deficit mutant seeds. A biochemical staining approach was used to detect tissue localizations of peroxidase activities in PA-deficit mutant seeds.

KEY RESULTS

PA-deficient mutants possess significantly lower levels of H2O2 than the wild-type, despite their higher accumulation of superoxide radicals. Screening of the key antioxidant enzymes revealed that peroxidase activity was significantly over-activated in mutant seeds. This high peroxidase activity was mainly confined to the seed coat zone. Interestingly, neither ascorbate peroxidase nor glutathione peroxidase, just the guaiacol peroxidases (class III peroxidases), was specifically activated in the seed coat. However, no significant difference in peroxidase activity was observed in embryos of either mutants or the wild-type, although gene expressions of several candidate peroxidases were down-regulated in the embryos of PA-deficient seeds.

CONCLUSIONS

The results suggest that enhanced class III peroxidase activity in the seed coat of PA-deficient mutants is an adaptive strategy for seed development and survival.

Progress in phage display: evolution of the technique and its application

Phage display, the presentation of (poly)peptides as fusions to capsid proteins on the surface of bacterial viruses, celebrates its 25th birthday in 2010. The technique, coupled with in vitro selection, enables rapid identification and optimization of proteins based on their structural or functional properties. In the last two decades, it has advanced tremendously and has become widely accepted by the scientific community. This by no means exhaustive review aims to inform the reader of the key modifications in phage display. Novel display formats, innovative library designs and screening strategies are discussed. I will also briefly review some recent uses of the technology to illustrate its incredible versatility.

Chromato-panning: an efficient new mode of identifying suitable ligands from phage display libraries

BACKGROUND

Phage Display technology is a well established technique for high throughput screening of affinity ligands. Here we describe a new compact chromato-panning procedure for selection of suitable binders from a phage peptide display library.

RESULTS

Both phages and E. coli cells pass non-hindered through the interconnected pores of macroporous gel, so called cryogel. After coupling a ligand to a monolithic cryogel column, the phage library was applied on the column and non-bound phages were washed out. The selection of strong phage-binders was achieved already after the first panning cycle due to the efficient separation of phage-binders from phage-non-binders in chromatographic mode rather than in batch mode as in traditional biopanning procedures. E. coli cells were applied on the column for infection with the specifically bound phages.

CONCLUSION

Chromato-panning allows combining several steps of the panning procedure resulting in 4-8 fold decrease of total time needed for phage selection.

Cryogel applications in microbiology

There is a great demand for improved technologies with regard to rapid processing of nano- and microparticles. The handling of viruses in addition to microbial and mammalian cells requires the availability of appropriate adsorbents. Recent developments in macroporous gels produced at subzero temperatures (known as cryogels) have demonstrated an efficiency for processing cell and virus suspensions, cell separation and cell culture applications. Their unique combination of properties such as macroporosity, tissue-like elasticity and biocompatibility, physical and chemical stability and ease of preparation, renders these materials interesting candidates for a broad range of potential applications within microbiological research. This review describes current applications of macroporous cryogels in microbiology with a brief discussion of future perspectives.

Selecting and screening recombinant antibody libraries

During the past decade several display methods and other library screening techniques have been developed for isolating monoclonal antibodies (mAbs) from large collections of recombinant antibody fragments. These technologies are now widely exploited to build human antibodies with high affinity and specificity. Clever antibody library designs and selection concepts are now able to identify mAb leads with virtually any specificity. Innovative strategies enable directed evolution of binding sites with ultra-high affinity, high stability and increased potency, sometimes to a level that cannot be achieved by immunization. Automation of the technology is making it possible to identify hundreds of different antibody leads to a single therapeutic target. With the first antibody of this new generation, adalimumab (Humira, a human IgG1 specific for human tumor necrosis factor (TNF)), already approved for therapy and with many more in clinical trials, these recombinant antibody technologies will provide a solid basis for the discovery of antibody-based biopharmaceuticals, diagnostics and research reagents for decades to come.