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bioRxiv · 10.1101/2021.10.29.466426

Essential elements of radical pair magnetosensitivity in Drosophila

Bradlaugh, A.·Fedele, G.·Munro, A.·Hansen, C.·Kyriacou, C.·Jones, A. R.·Rosato, E.·Baines, R.
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Abstract

Many animals use the Earths magnetic field (geoMF) for navigation1. The favored mechanism for magnetosensitivity involves a blue-light (BL) activated electron transfer reaction between flavin adenine dinucleotide (FAD) and a chain of tryptophan (Trp) residues within the photoreceptor protein, CRYPTOCHROME (CRY). The spin-state of the resultant radical pair (RP), and hence the concentration of CRY in its active state, is influenced by the geoMF2. The canonical CRY-centric radical pair mechanism (RPM) does not, however, explain many physiological and behavioural observations2-8. Here, using electrophysiology and behavioural analyses, we assay magnetic field (MF) responses at single neuron and organismal level. We show that the 52 C-terminal (CT) amino acids of CRY, which are missing the canonical FAD binding domain and Trp chain, are sufficient to facilitate magnetoreception. We also show that increasing intracellular FAD potentiates both BL-induced and MF-dependent effects on the activity mediated by the CT. Additionally, high levels of FAD alone are sufficient to cause BL neuronal sensitivity and, remarkably, potentiation of this response in the co-presence of a MF. These unexpected results reveal the essential components of a primary magnetoreceptor in flies, providing strong evidence that non-canonical (i.e., non-CRY-dependent) RPs can elicit MF responses in cells.

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Bradlaugh, A., Fedele, G., Munro, A., Hansen, C., Kyriacou, C., Jones, A. R., Rosato, E., Baines, R.. 2021-11-01. Essential elements of radical pair magnetosensitivity in Drosophila. https://doi.org/10.1101/2021.10.29.466426

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