Fig. 7: The working models of dCry. | Communications Chemistry

Fig. 7: The working models of dCry.

From: The ionic and protonation states of flavin control the activation and recovery of Drosophila cryptochrome

Fig. 7

A The negative charge and conformational changes of the FAD cofactor regulate CTT release. Wild-type dCry can be photoreduced to a large fraction of the asq state (FAD●−) and a small fraction of the nsq state (FADH●) under neutral conditions. The hq state (FADH−) can only be obtained in some dCry mutants (such as C416N and L405E/C416N) after prolonged illumination. The asq state and the hq state FAD trigger CTT release. B His378 of dCry adjusts the protonation degree of FAD during photoreduction to achieve a balance between light sensitivity and dark recovery. In the L405E/C416N mutant, the FAD cofactor can be efficiently protonated through the Glu405 site during short-term photoreduction, resulting in a nearly pure nsq state. Both of the light sensitivity and dark recovery of L405E/C416N are inhibited (in the Asn416 background). In the F535A or W536A mutant, the FAD protonation is suppressed during photoreduction, resulting in a nearly pure asq state. The light sensitivity of F535A or W536A is increased, but their dark recovery is impaired.

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