AUTHOR=Mazzotta Gabriella Margherita , Bellanda Massimo , Minervini Giovanni , Damulewicz Milena , Cusumano Paola , Aufiero Simona , Stefani Monica , Zambelli Barbara , Mammi Stefano , Costa Rodolfo , Tosatto Silvio C. E. 

TITLE=Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors

JOURNAL=Frontiers in Molecular Neuroscience

VOLUME=Volume 11 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2018.00280

DOI=10.3389/fnmol.2018.00280

ISSN=1662-5099

ABSTRACT=Light is the main environmental stimulus that synchronizes the endogenous timekeeping systems in most terrestrial organisms. Drosophila cryptochrome (dCRY) is a light-responsive flavoprotein that detects changes in light intensity and wavelength around dawn and dusk. We have previously shown that dCRY acts through INAD (Inactivation No Afterpotential D) in a light-dependent manner on the Signalplex, a multiprotein complex that includes visual-signaling molecules, suggesting a role for dCRY in fly vision. Here, we predict and demonstrate a novel Ca2+-dependent interaction between dCRY and calmodulin (CaM). Through in yeast two hybrid, Co-IP, NMR, and calorimetric analyses we were able to identify and characterize a CaM binding motif in the dCRY N-terminus. Similarly, we also detailed the CaM binding site of the scaffold protein INAD and demonstrated that CaM bridges dCRY and INAD to form a ternary complex in vivo. Our results suggest a process whereby a rapid dCRY light response stimulates an interaction with INAD, which can be further consolidated by a novel mechanism regulated by CaM.