Seminar
professor Kazuya Kikuchi
Osaka University
Graduate School of Engineering
WPI-Immunology Frontier Research Center
Osaka, Japan
Title: Design, synthesis and biological application of in vivo imaging probes with tunable chemical switches
Host: Gunnar Öquist
Place: KBC, Large Lecture hall "Stora hörsalen"
Abstract:
One of the great challenges in the post-genome era is to clarify the biological significance of intracellular molecules directly in living cells. If we can image a molecule in action, it is possible to acquire biological information, which is unavailable if we deal with cell homogenates. One possible approach is to design and synthesize chemical probes that can convert biological information to chemical output. Protein fluorescent labeling provides an attractive approach to study the localization and function of proteins in living cells. Recently, a specific pair of a protein tag and its ligand has been utilized to visualize a protein of interest (POI). In this method, a POI is fused with a protein tag and the tag is labeled with the ligand connected to a fluorescent molecule. The advantage of this protein labeling system is that a variety of fluorescent molecules are potentially available as labeling reagents, and that the protein tag is conditionally labeled with its fluorescent ligand. I have designed a protein labeling system that allows fluorophores to be linked to POI. The protein tag (BL-tag) is a mutant class A ?-lactamase (TEM-1) modified to be covalently bound to the designed specific labeling probes and the labeling probes is consisted with a ?-lactam ring (ampicillin, cephalosporin) attached to various fluorophores. A fluorogenetic labeling system can be designed using the unique property of cephalosporin, which release leaving group by subsequent reaction after opening the lactam ring. For further sophisticated application, multicolor imaging was done by adopting the colorful fluorophores.