Santos EM, Berbasova T, Wang W, Salmani RE, Sheng W, Vasileiou C, Geiger JH, Borhan B. Engineering of a Red Fluorogenic Protein/Merocyanine Complex for Live-Cell Imaging.
Chembiochem 2020;
21:723-729. [PMID:
31482666 PMCID:
PMC7379159 DOI:
10.1002/cbic.201900428]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Indexed: 12/25/2022]
Abstract
A reengineered human cellular retinol binding protein II (hCRBPII), a 15-kDa protein belonging to the intracellular lipid binding protein (iLBP) family, generates a highly fluorescent red pigment through the covalent linkage of a merocyanine aldehyde to an active site lysine residue. The complex exhibits "turn-on" fluorescence, due to a weakly fluorescent aldehyde that "lights up" with subsequent formation of a strongly fluorescent merocyanine dye within the binding pocket of the protein. Cellular penetration of merocyanine is rapid, and fluorophore maturation is nearly instantaneous. The hCRBPII/merocyanine complex displays high quantum yield, low cytotoxicity, specificity in labeling organelles, and compatibility in both cancer cell lines and yeast cells. The hCRBPII/merocyanine tag is brighter than most common red fluorescent proteins.
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