Abstract
BackgroundFolate-dependent one-carbon metabolism provides one-carbon units for several biological processes. This pathway is highly compartmentalized in eukaryotes, with the mitochondrial pathway producing formate for use in cytoplasmic processes. The mitochondrial enzyme MTHFD2 has been reported to use NAD+ as a cofactor while the isozyme MTHFD2L utilizes NAD+ or NADP+ at physiologically relevant conditions. Because MTHFD2 is highly expressed in many cancer types, we sought to determine the cofactor preference of this enzyme.ResultsKinetic analysis shows that purified human MTHFD2 exhibits dual redox cofactor specificity, utilizing either NADP+ or NAD+ with the more physiologically relevant pentaglutamate folate substrate.ConclusionThese results show that the mitochondrial folate pathway isozymes MTHFD2 and MTHFD2L both exhibit dual redox cofactor specificity. Our kinetic analysis clearly supports a role for MTHFD2 in mitochondrial NADPH production, indicating that this enzyme is likely responsible for mitochondrial production of both NADH and NADPH in rapidly proliferating cells.
Highlights
Folate-dependent one-carbon metabolism provides one-carbon units for several biological processes
One-carbon metabolism is highly compartmentalized in eukaryotes [3], and mitochondria play a critical role in cellular 1C metabolism
Understanding how MTHFD2 is involved in both of these biological processes is of critical importance to effectively develop therapeutics targeting this enzyme for cancer treatment
Summary
Folate-dependent one-carbon metabolism provides one-carbon units for several biological processes. One-carbon (1C) metabolism is a universal folatedependent pathway that generates 1C units for de novo purine and thymidylate synthesis, interconversion of several amino acids, production of universal methyl donors, and regeneration of redox cofactors. Because these metabolic processes play critical roles in cancer cells [1, 2], 1C metabolism has long been an important target for the development of chemotherapeutic drugs. MTHFD1L is a monofunctional 10CHO-THF synthetase [9] It catalyzes the final step in the mitochondrial pathway to produce formate, controlling the flux of 1C units from mitochondria into cytoplasmic processes
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