Selective fluorophore-labeling of newly synthesized proteins

ORGN 876

Kimberly E. Beatty, beatty@caltech.edu, Julie C. Liu, julieliu@caltech.edu, and David A. Tirrell, tirrell@caltech.edu. Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd, MC 210-41, Pasadena, CA 91125
Proteomic investigations enable the identification of proteins from whole cells or isolated organelles. Such studies would be augmented by direct visualization of the proteins of interest. Recently, Beatty and coworkers reported the visualization of newly synthesized proteins in bacterial cells through the co-translational introduction of an alkynyl amino acid. After incorporation, proteins containing the non-canonical amino acid underwent a highly selective Cu(I)-catalyzed reaction with fluorogenic 3-azido-7-hydroxycoumarin dye. As a powerful extension of this work, we have demonstrated fluorescent labeling of newly synthesized proteins inside a diverse set of mammalian cells. Labeling was analyzed using flow cytometry and fluorescence microscopy. Fluorescent micrographs of labeling showed that a subset of new proteins is localized in nucleoli.