Daiwen Yang (Professor)
1. Development of virus-like particles as vaccines
Virus-like particles (VLPs) are multimeric protein complexes, which have similar shapes to the naturally occurring viruses and can elicit strong immune responses but are non-infectious as they contain no viral genetic material. VLPs can be generated through self-assembly of viral structural proteins (such as capsid proteins), which are often produced in recombinant DNA technology. One ongoing project is to use the VLP-based method to develop immersion and oral vaccines against fish virus diseases. The efficacy of the developed vaccines are tested on fish in our collaborator’s laboratory.
VLPs can also be used as a display device for the development of vaccines against cancer and infectious diseases. Thus VLPs can serve as powerful immunotherapy platforms. The principle is to link cancer-specific antigens (which is located on the cell surfaces of only cancer cells) or other antigens to VLPs. The antigens displayed on the VLPs can induce stronger immune response than the isolated antigens alone. Currently, we are working in two areas: one displaying cancer-specific antigens on VLPs and the other displaying bacterial surface antigens. In order to reduce the effect of the displayed antigens on VLP stability, we also engineer wild-type capsid proteins to incorporate various antigens. The efficacy of the developed vaccines are evaluated in cell lines and then in animal models.
2. Fatty acid binding proteins and structure-based drug design
Fatty acid binding proteins (FABPs) are a cluster of specific carrier proteins that actively facilitate the transport of fatty acids to specific organelles in the cell for metabolism, storage, and signaling. They are critical meditators of metabolism and inflammatory processes and are considered as promising therapeutic targets for metabolic diseases. Nine types of FABPs (FABP1-9) are found in the cytosol of a variety of mammalian tissues and some are detected in human serum. Besides the common role as fatty acid carriers, FABPs may play other roles in different biological processes since FABP4 (adipocyte FABP) is implicated in diabetes, FABP1 (liver FABP) is related to kidney and non-alcoholic liver diseases, and FABP3 (heart FABP) is associated with neurodegenerative diseases such as Alzheimer’s.
Because the differential functional roles of different FABPs cannot be explained by the structures alone, we have been studying the dynamics that is currently the missing link between the protein structure and function using mutagenesis, NMR, MS and molecular dynamics simulation. We aim to understand how different FABPs play differential functions and to design inhibitors and nanobodies that selectively target one FABP. Identification of true inhibitors is achieved using bioassays and NMR-based screening, while nanobody identification is achieved using a de novo designed nanobody library based on the phage display technique. Functional tests are performed on animal models.
3. Mechanism of silk fiber formation and production of engineered spider silk and functionalized fibers
Spider silk is orderly assembled from one or more silk proteins. Due to its outstanding mechanical property, lightness, biodegradability and biocompatibility, spider silk is a super material with substantial potential in medicine and industry. Unfortunately, spider silk is not available commercially because spiders are cannibalistic and territorial and thus cannot be farmed. To make spider silk available on a large scale, various recombinant methods have been attempted but with limited success due to our poor understanding of the molecular mechanism of silk fiber formation and the silk structure-property relationship.
We focus on the structures of silk proteins, production of spider silk from recombinant silk proteins, and generation of silk fibers with various biochemical functions. To reveal the fiber formation mechanism and silk property-structure relationship, we have been studying the structures of silk proteins at different stages of fiber formation using biophysical techniques such as nuclear magnetic resonance spectroscopy (NMR), electron microscopy (EM), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and mass spectrometry (MS). It is noteworthy that silk formation involves dramatic changes from water-soluble proteins with dominant random-coil or α-helical structures to insoluble silk fibers with dominant β-sheet structures. In order to produce super silk, we have been engineering silk proteins by molecular biology techniques for high yield production and developing microfluidic device for spinning protein solution into strong silk. Silk proteins can be easily modified by fusing them with enzymes or other functional proteins or by chemical modification. Using such modified proteins, we are producing functional biomaterials.
4. Development of NMR and computational methods for protein structure determination and dynamics characterization
To overcome difficulties encountered in our characterization of protein structures and dynamics, we develop novel NMR experiments and new computational methods.
- 2011 – present: Professor, Department of Biological Sciences, National University of Singapore.
- 2005 – 2011: Associate professor, Department of Biological Sciences, National University of Singapore.
- 2001 – 2005: Assistant professor, Department of Biological Sciences and Department of Chemistry, National University of Singapore.
- 1997 – 2000: Research associate, Department of Medical Genetics, University of Toronto, Canada.
- 1995 – 1997: Postdoctoral research fellow, Department of Medical Genetics, University of Toronto, Canada.
- 1992 – 1995: Postdoctoral research fellow, Nagayama protein array project, ERATO, JRDC, Japan.
- Department of Biological Sciences, National University of Singapore
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