Primary structure of a folate-dependent trifunctional enzyme from Spodoptera frugiperda

The dehydrogenase and synthetase activities of the NADP-dependent methylenetetra-hydrofolate dehydrogenase-cyclohydrolase-synthetase are undetectable in extracts of the Spodoptera frugiperda cell line, Sf9. However, a single cDNA encoding this protein was isolated from a library and sequenced. The deduced amino acid sequence codes for a protein of 933 amino acids in length that shows 59% identity to the human enzyme. The cDNA inserted in the yeast expression vector pVT102-U complements a purine auxotrophic yeast strain lacking this enzyme.