Improved Photostable FRET-Competent Biarsenical−Tetracysteine Probes Based on Fluorinated Fluoresceins
作者:Carla C. Spagnuolo、Rudolf J. Vermeij、Elizabeth A. Jares-Erijman
DOI:10.1021/ja063212q
日期:2006.9.1
We have developed fluoro-substituted versions of the biarsenical-tetracysteine label FlAsH, exhibiting significant improvements in important properties over the original fluorescein derivative. In complexes with tetracysteine targets, F2FlAsH exhibits 50 times improved photostability, lower pH sensitivity, higher absorbance and quantum yield than FlAsH, and F4FlAsH adds a new color to the palette of biarsenical dyes. The two probes also provide a new FRET pair with a larger Ro value (54 A) than any previously obtained with biarsenical dyes.
Tetracysteine-tagged prion protein allows discrimination between the native and converted forms
The conformational conversion of prion protein (PrP) from a native conformation to the amyloid form is a hallmark of transmissible spongiform encephalopathies. Conversion is usually monitored by fluorescent dyes, which bind generic amyloids and are less suited for living cell imaging. We report a new method for the synthesis of membrane‐permeable and membrane‐impermeable biarsenical reagents, which are then used to monitor murine PrP (mPrP) misfolding. We introduced tetracysteine (TC) tags into three different positions of mPrP, which folded into a native‐like structure. Whereas mPrPs with a TC tag inserted at the N‐terminus or C‐terminus supported fibril formation, insertion into the helix 2–helix 3 loop inhibited conversion. We devised a quantitative protease‐free method to determine the fraction of converted PrP, based on the ability of the fluorescein arsenical helix binder reagent to differentiate between the monomeric and fibrilized form of TC‐tagged PrP, and showed that TC‐tagged mPrP could be detected on transfected cells, thereby expanding the potential use of this method for the detection and study of conformational diseases.Structured digital abstractMINT‐7709757: Prp (uniprotkb:P04925) and Prp (uniprotkb:P04925) bind (MI:0407) by electron microscopy (MI:0040)MINT‐7709744: Prp (uniprotkb:P04925) and Prp (uniprotkb:P04925) bind (MI:0407) by circular dichroism (MI:0016)MINT‐7709730: Prp (uniprotkb:P04925) and Prp (uniprotkb:P04925) bind (MI:0407) by fluorescence technology (MI:0051)