Thymidylate synthase and folate pathway enzymes (TS/Folate pathway)

Thymidylate synthase (TS) and related folate pathway enzymes, such as dihydrofolate reductase (DHFR), are central to the one-carbon metabolism cycle required for the de novo synthesis of DNA precursors (UniProt P04818, P00374). TS catalyzes the conversion of deoxyuridylate (dUMP) to deoxythymidylate (dTMP), providing the only intracellular source of thymidine for DNA synthesis and repair (PubMed: 15150105). DHFR maintains the pool of reduced folates by converting dihydrofolate into tetrahydrofolate, a necessary cofactor for TS and enzymes involved in purine biosynthesis like glycinamide ribonucleotide transformylase (StatPearls: Antifolate Medications). Because rapidly dividing cells have a high demand for nucleotides, these enzymes are primary targets in oncology, where their inhibition leads to "thymineless death" and cell cycle arrest (NCBI: PMC3654875). Beyond cancer, these pathways are targeted in autoimmune diseases like rheumatoid arthritis and in infectious diseases to exploit differences between host and pathogen folate metabolism (PubChem). Clinical challenges include significant side effects like myelosuppression and the emergence of resistance through enzyme overexpression or mutations in folate transporters (PubMed: 11414342).

Other names

Thymidylate synthaseDihydrofolate reductaseTYMSDHFRFolate metabolism enzymesAntifolate targetsPurine pathway enzymesOne-carbon metabolism enzymes

Inhibition of deoxythymidylate (dTMP) synthesis and purine biosynthesis through the depletion of reduced folate cofactors or direct active site competition, leading to DNA synthesis inhibition and thymineless cell death.