Pavlic, A. | bioRxiv Science

bioRxiv2026

Cytosolic MagLOV Magnetofluorescence in Mammalian Cell Lines and Primary Neurons

Magnetic fields can influence the outcome of photochemical reactions through the radical pair mechanism, but whether this sensitivity extends to standard experimental conditions in mammalian cells has remained unclear. Here, we quantify the cytosolic magnetofluorescence of MagLOV, a genetically encoded, flavin-binding fluorescent protein, in mammalian cells, validated against extensive artifact controls. Excitation intensity and magnetic field strength differentially tune response kinetics and amplitude, respectively, with amplitude saturating above approximately 8 mT. Magnetic field-effect amplitude is further modulated by cellular culture state. This response generalizes across HEK293T, HeLa, U2OS, and A549 cells and primary mouse cortical neurons, with plateau amplitudes ranging from 1.4% to 2.7%. Together, these results establish that genetically encoded spin-dependent photochemistry can be quantitatively interrogated under standard mammalian live-cell imaging conditions, and generalizes across mammalian cell types.

biophysics↗

bioRxiv2025

Rewiring protein function through genetically encoded oxidative chemistry

Oxidative chemistry underlies many endogenous signaling pathways but remains underutilized as a programmable strategy for regulating protein function in living cells. Here we establish genetically encoded oxidative chemistry as a tunable framework for modulating diverse proteins by coupling a photosensitizer to defined intracellular contexts. Using miniSOG to generate reactive oxygen species (ROS), we show that controlled intracellular oxidation increases the fluorescence of the redox reporter HyPerRed and activates redox-sensitive TRP ion channels, with strong responses in TRPA1 and TRPV1 but not TRPV4. Pathway-selective scavengers reveal differential coupling of soluble and membrane targets to distinct oxidative processes, supporting selectivity by context rather than uniform oxidative perturbation. Modulation strength and kinetics are quantitatively tunable through illumination parameters, expression ratios, and subcellular localization, with membrane targeting enhancing coupling to membrane effectors. Finally, fusion targeting of miniSOG to TRPV1 and modulation of endogenous TRPA1 in human fibroblasts extend this approach to protein-proximal and native cellular settings. Together, these results position genetically encoded oxidative chemistry as a versatile and spatially organized modality for engineering protein function in living cells within a defined operating regime.

synthetic biology↗