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bioRxiv · 10.1101/2025.08.06.668860

Structural assembly of maize CRY-GL2 photosignaling complex provides insights into its regulatory role in cuticular wax biosynthesis

Liu, Y.·Zhao, Z.·Zhang, X.·Hao, Y.·Feng, F.·Chen, Y.·Wang, J.·MA, M.·LI, J.·Yu, F.·Liu, H.·Zhang, P.
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Abstract

Cryptochromes (CRYs) are blue-light photoreceptors in plants that regulate diverse physiological processes through oligomerization-dependent interactions with downstream effectors. While numerous light-inducible CRY-binding proteins have been identified, the structural basis for photoactivated CRY-effector assembly remains poorly understood. Here we report the crystal structure of a constitutively active maize CRY1c photolyase homology region (ZmCRY1c-PHRW368A) in complex with ZmGL2, a BAHD ptotein directing very-long-chain fatty acid (VLCFA) elongation for cuticular wax biosynthesis. Structural analysis reveals that light-activated ZmCRY1c forms a homotetrameric scaffold generating four symmetric binding sites at subunit interfaces. Each ZmCRY1c protomer engages one ZmGL2 molecule through conformational reorganization of its 16-17 loop and 17 helix, establishing a 4:4 hetero-octameric photosignaling complex validated by mutational profiling and optical design. Remarkably, structural alignment with the ZmCER6-ZmGL2 complex reveals substantial overlap (78%) in ZmGL2 binding interfaces. Biochemical quantification demonstrates that ZmCRY1c suppresses ZmCER6-GL2 enzyme activity in a dose dependent manner, unveiling a light-dependent regulatory switch controlling VLCFA elongation efficiency, though in vivo physiological investigation is awaited. Collectively, our work not only establishes the atomic model of light-activated plant CRY-effector assembly, but also uncovers a previously unrecognized spatial competition between photoreceptor and metabolic enzyme complexes that might function as a photoregulatory paradigm in cuticular wax biosynthesis.

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Liu, Y., Zhao, Z., Zhang, X., Hao, Y., Feng, F., Chen, Y., Wang, J., MA, M., LI, J., Yu, F., Liu, H., Zhang, P.. 2025-08-07. Structural assembly of maize CRY-GL2 photosignaling complex provides insights into its regulatory role in cuticular wax biosynthesis. https://doi.org/10.1101/2025.08.06.668860

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