Bradlaugh, A.A., Fedele, G., Munro, A.L., Hansen, C.N., Hares, J.M., Patel, S., Kyriacou, C.P., Jones, A.R., Rosato, E., Baines, R.A. (2023). Essential elements of radical pair magnetosensitivity in Drosophila.  Nature 615(7950): 111--116.

FBrf0255939

Research paper

Many animals use Earth's magnetic field (also known as the geomagnetic field) for navigation[1]. The favoured mechanism for magnetosensitivity involves a blue-light-activated electron-transfer reaction between flavin adenine dinucleotide (FAD) and a chain of tryptophan residues within the photoreceptor protein CRYPTOCHROME (CRY). The spin-state of the resultant radical pair, and therefore the concentration of CRY in its active state, is influenced by the geomagnetic field[2]. However, the canonical CRY-centric radical-pair mechanism does not explain many physiological and behavioural observations[2-8]. Here, using electrophysiology and behavioural analyses, we assay magnetic-field responses at the single-neuron and organismal levels. We show that the 52 C-terminal amino acid residues of Drosophila melanogaster CRY, lacking the canonical FAD-binding domain and tryptophan chain, are sufficient to facilitate magnetoreception. We also show that increasing intracellular FAD potentiates both blue-light-induced and magnetic-field-dependent effects on the activity mediated by the C terminus. High levels of FAD alone are sufficient to cause blue-light neuronal sensitivity and, notably, the potentiation of this response in the co-presence of a magnetic field. These results reveal the essential components of a primary magnetoreceptor in flies, providing strong evidence that non-canonical (that is, non-CRY-dependent) radical pairs can elicit magnetic-field responses in cells.

PMC9977682 (PMC) (EuropePMC)