Mediates blue light-induced gene expression in addition to its role in blue light-dependent inhibition of stem growth. Binds 1 FAD per subunit. Binds 1 5,10-methenyltetrahydrofolate (MTHF) per subunit. Homodimer. By visible light. Belongs to the DNA photolyase class-1 family. Was originally thought to be a DNA photolyase.