May have a photoreceptor function. Binds DNA; probably functions as a transcriptional repressor (By similarity). Has no photolyase activity. Upon purification from either V.cholerae or E.coli an approximately 60 nucleotide RNA is associated with the protein. Binds 1 FAD per subunit. Binds 1 5,10-methenyltetrahydrofolate (MTHF) non-covalently per subunit. Binds the MTHF cofactor more tightly than the FAD cofactor. Belongs to the DNA photolyase class-1 family.