SNAP-Tag-Based Subcellular Protein Labeling and Fluorescent Imaging with Naphthalimides

5 years ago

SNAP-Tag-Based Subcellular Protein Labeling and Fluorescent Imaging with Naphthalimides

Yi Xiao, Xinbo Song, Chao Wang

Genetically encoded technologies provide methods for the specific labeling and imaging of proteins, which is essential to understand the subcellular localization of these proteins and their function. Herein, we employed naphthalimide, an efficient two-photon fluorophore, to develop O6-benzylguanine (BG) derivatives for specific labeling of subcellular proteins and fluorescent imaging through the SNAP-tag. Three naphthalimide–BG derivatives, TNI-BG, QNI-BG, and ONI-BG, were conveniently synthesized through modular “click chemistry” in high yields. All of them showed high labeling efficiency with SNAP-tag in solution (≈1–2×103 s−1 m−1) and in bacteria. Among them, ONI-BG showed high specificity to diffused, histone H2B and mitochondria COX8A targeted SNAP-tag in mammalian cells. The protein-labeled naphthalimides exhibited high two-photon absorption cross-sections, which indicated their potential application in protein-specific two-photon fluorescent imaging, such as two-photon fluorescent lifetime imaging and two-photon multicolor imaging. Therefore, ONI-BG is a versatile tool that can be used to track subcellular proteins through multiple fluorescent techniques. SNAP to it! A two-photon naphthalimide dye was used to develop O6-benzylguanine (BG) derivatives for the specific labeling of subcellular proteins and fluorescent imaging through the SNAP-tag. All showed high labeling efficiency with SNAP-tag in vitro and in bacteria cells, but only one showed highly specific labeling in mammalian cells.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/cbic.201700161