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Biological systems are highly complicated but at the same time remarkably precise and dynamic. These systems are built through well-organized self- (or assisted-) assembly processes of various biomolecules such as DNA/RNA, proteins, and lipids. Many artificial biomolecular assemblies have been investigated with the aim of understanding natural assembly processes as well as devising novel biomolecular architectures with new structures and functions.
Protein multivalency, particularly multivalent protein interactions, is a key principle in many biological processes ranging from cell-cell communications, viral entry, and immune responses to, more recently, biomolecular phase separations. However, little is known about the principles of multivalent protein interactions, which can achieve highly enhanced but also dynamic binding between various biological systems. High-order protein scaffolds, such as those fabricated in our lab, will be highly beneficial tools not only to study but also to use and control protein multivalency.
The main purpose of our research is to create new biochemical (biomolecular) probes/scaffolds, and apply them for the development of new bioanalytical tools, by which offering unprecedented and distinct ways to study this fascinating phenomena of biomolecular multivalency (or bio-assembly). Our targets of interests are small RNAs, viruses, unfolded fibrogenic proteins, clustering biomolecules, and lipid bilayers. Probes for target binding, signal generating, versatile linking, and multivalent scaffolds will be developed and collectively used for the analysis.
Frequently used research techniques in our Lab are nucleic acids/protein engineering; high-order biomolecule assembling; biomolecular interaction analysis; structural analysis, cellular imaging, etc ...
Here we introduce two of our recent projects.
1. GFP polygons
Supramolecular protein assemblies (also called protein nanostructures) provide novel nano-architectures with molecular precision and unlimited functionalities. Ideally, one would like to direct spatial organization of functional proteins with tailored structures and sizes.
Recently, we fabricated green fluorescent protein (GFP) assemblies with well-defined polygonal structures (protein nanopolygon) from dimer to decagon in a monodisperse (discrete) population. Spatial arrangements of GFP polygons and displayed functional proteins were directly visualized by TEM. We also demonstrated how functionalized GFP polygons offer unprecedented tools to design experiments to understand principles of multivalent protein interactions and receptor clustering on cell surfaces.
Reference: Kim YE, Kim Yn, Kim JA, Kim HM, and Jung Y*, "Green fluorescent protein nanopolygons as monodisperse supramolecular assemblies of functional proteins with defined valency", Nature Communications (2015), 6, 7134
2. Enhanced MonoAvidin (eMA)
(Strept)avidin and biotin (with their extremely strong interaction) have been one of the most widely used linking/labeling pairs in the biochemical and nano sciences. The tetrameric nature of (strept)avidin proteins, however, can result in undesirable (and uncontrollable) crosslinking of biotinylated molecules. Therefore, developing a monomeric avidin protein with a highly stable biotin binding property has been a major challenge over a decade.
Recently, we reported a monomeric avidin-like protein (enhanced monoavidin, eMA) that shows almost multimeric avidin-like binding stability against various biotin-conjugates. Our eMA (~14 kDa) offers the first practically applicable monomeric avidin linker, which allows truly monomeric biotin labeling with minimal perturbation. In addition, eMA can be fused to diverse multimeric proteins to create new multivalent avidin probes with precise spatial organization and defined valency of biotin binding sites, which we showed by fabricating an unprecedented 24-meric avidin probe.
Reference: Lee JM, Kim JA, Yen TC, Lee IH, Ahn B, Lee Y, Hsieh CL, Kim HM, and Jung Y*, "A Rhizavidin Monomer with Nearly Multimeric Avidin-Like Binding Stability Against Biotin Conjugates", Angewandte Chemie Int. Ed. (2016), 55, 3393-3397. |
