Enzyme's Surprising Twist: A New Role in Metabolic Control
In a groundbreaking discovery, researchers have uncovered a hidden talent of an enzyme, challenging our understanding of its traditional role. This revelation has significant implications for metabolic disorders and cancer treatment.
(Vienna, November 6, 2025) Imagine a bustling city, where every building has a specific function, and a disruption in any one of them can cause chaos. Similarly, inside our cells, a complex metabolic network orchestrates the production and recycling of essential molecules. One such crucial process is folate metabolism, which provides the building blocks for DNA, RNA, and amino acids. When this system malfunctions, it can lead to severe disorders, including cancer.
And here's where it gets intriguing: scientists from CeMM, the Research Center for Molecular Medicine, and the University of Oxford, have identified an enzyme, NUDT5, as an unexpected hero in this metabolic drama. Their research, published in the prestigious journal Science, reveals a surprising twist in NUDT5's role.
A New Role for an Old Enzyme
Purines, the focus of this story, are vital molecules that cells use for DNA and RNA construction and energy storage. They can be recycled or created from scratch through the de novo pathway, a process that demands tight regulation due to its energy intensity.
The researchers delved into this control mechanism by studying cells with mutations in MTHFD1, a gene encoding a critical enzyme in the folate cycle. Folate metabolism is essential as it provides the one-carbon units needed for purine synthesis, and disruptions here can lead to rare genetic diseases and influence cancer risk.
Using advanced techniques, the team discovered a fascinating interaction between NUDT5 and PPAT, an enzyme that initiates purine synthesis. When purine levels increase, NUDT5 binds to PPAT, seemingly locking it into an inactive state, signaling the cell to halt purine production.
But here's the twist: NUDT5 doesn't rely on its enzymatic activity to perform this function! Even when its catalytic site was blocked, it continued to regulate purine synthesis. Only when NUDT5 was completely removed did cells lose this control.
Metabolic Control with Medical Significance
This discovery opens a new chapter in our understanding of cellular metabolism. "NUDT5 has traditionally been known for its enzymatic activity in metabolite hydrolysis," says Stefan Kubicek, a senior researcher at CeMM. "However, our study reveals its surprising role as a structural regulator, deciding whether cells continue producing purines."
Controversial Implications for Cancer Treatment
This mechanism may explain why some cancer cells become resistant to chemotherapy. Certain drugs mimic purine molecules to block DNA synthesis, but cells lacking the NUDT5-PPAT interaction are less affected by these treatments, suggesting NUDT5 mutations could contribute to drug resistance. This idea is supported by similar findings from Ralph DeBerardinis' lab, published in the same issue of Science.
The research also connects folate metabolism, purine synthesis, and diseases caused by MTHFD1 deficiency, a rare genetic disorder. Understanding this regulatory network could lead to innovative therapies.
The Oxford team also developed dNUDT5, a chemical degrader that selectively removes NUDT5 from cells, offering a powerful tool for future research and potential protection of healthy cells during chemotherapy.
"Enzymes can influence cellular processes not only through their chemical reactions but also through their physical structure," Kubicek emphasizes. "This discovery invites us to explore the multifaceted roles of enzymes in cellular control."
This study challenges our assumptions about enzyme functions and highlights the complexity of cellular metabolism. What other hidden talents might enzymes possess? And how might this knowledge impact our approach to treating metabolic disorders and cancer? The scientific community eagerly awaits further exploration of these questions.
