Semisynthetic biosensors for mapping cellular concentrations of nicotinamide adenine dinucleotides.

Sallin, Olivier; Reymond, Luc; Gondrand, Corentin; Raith, Fabio; Koch, Birgit; Johnsson, Kai · Elife · 2018

basic_science · Level V

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Abstract

We introduce a new class of semisynthetic fluorescent biosensors for the quantification of free nicotinamide adenine dinucleotide (NAD<sup>+</sup>) and ratios of reduced to oxidized nicotinamide adenine dinucleotide phosphate (NADPH/NADP<sup>+</sup>) in live cells. Sensing is based on controlling the spatial proximity of two synthetic fluorophores by binding of NAD(P) to the protein component of the sensor. The sensors possess a large dynamic range, can be excited at long wavelengths, are pH-insensitive, have tunable response range and can be localized in different organelles. Ratios of free NADPH/NADP<sup>+</sup> are found to be higher in mitochondria compared to those found in the nucleus and the cytosol. By recording free NADPH/NADP<sup>+</sup> ratios in response to changes in environmental conditions, we observe how cells can react to such changes by adapting metabolic fluxes. Finally, we demonstrate how a comparison of the effect of drugs on cellular NAD(P) levels can be used to probe mechanisms of action.

Medical subject headings