Tuan‐Anh Nguyen, Jung-Ming G. Lin, Anne-Sophie M. C. Marques, Maximilian Fottner, Ludwig G. Bauer, Andreas Reicher, Diana Daum, Lorenzo Scrofani, Yusi Liu, Carol Cheng, Luna D’Angelo L.d.D., Juan Sánchez-Ávila, Christoph Bueschl, Nara Marella, Pisanu Buphamalai, Florian Traversi, Maša Bereš, Herwig P. Moll, Marton I. Siklos, Jakob‐Wendelin Genger, Gerald Hofstaetter, Ludovica Villanti, Monika Malik, Christoph Klimek, Kathrin Runggatscher, Bettina Guertl, Jesper S. Hansen, Sarah Dobner, Oľga Babošová, Tina Becirovic, Laura de Rooij, Emilio Casanova, Anna Koren, D. Sean Froese, David S. Rosenblatt, Kristaps Klavins, Andreas Bergthaler, Jörg Menche, J. Thomas Hannich, Miriam Abele, Sara Sdelci, Kathrin Lang, K. Huber, Stefan Kubicek
Folate metabolism is intricately linked to purine de novo synthesis through the incorporation of folate-derived one-carbon units into the purine scaffold. By investigating chemical and genetic dependencies caused by mutations in methylenetetrahydrofolate dehydrogenase, cyclohydrolase, and formyltetrahydrofolate synthetase 1 (MTHFD1), we discovered a key role for Nudix hydrolase 5 (NUDT5) in regulating purine de novo synthesis. Genetic depletion and selective chemical degradation showed that a scaffolding role, rather than NUDT5 enzymatic activity, was causing this phenotype. NUDT5 interacted with phosphoribosyl pyrophosphate amidotransferase (PPAT), the rate-limiting enzyme of purine de novo synthesis, to repress the pathway in response to increased purine abundance. Through this mechanism, loss of NUDT5 mediates resistance to purine analogs in cancer treatment and prevents adenosine toxicity in MTHFD1 deficiency.