Understanding how cells synthesize DNA building blocks could unlock new approaches to cancer treatment and aging research. The process depends on ribonucleotide reductase enzymes that convert RNA components into DNA precursors, but the precise mechanisms have remained elusive for decades.
Researchers have now mapped how metal-free ribonucleotide reductase achieves long-distance electron transfer through specialized hydrogen bonds. Unlike conventional hydrogen bonds, these low-barrier variants facilitate proton-coupled electron transfer across protein domains separated by significant molecular distances. The enzyme orchestrates radical chemistry by moving electrons through a carefully positioned network of amino acid residues, enabling the conversion of ribonucleotides to deoxyribonucleotides without requiring metal cofactors.
This discovery illuminates a fundamental biological process that operates in all dividing cells. Ribonucleotide reductases represent one of evolution's most ancient enzyme families, suggesting these electron transfer mechanisms emerged early in cellular evolution. The metal-free variant studied here offers particular insight because it accomplishes the same chemistry as metal-dependent versions through entirely different molecular architecture. Cancer cells rely heavily on ribonucleotide reductase activity to support rapid DNA synthesis, making these enzymes established chemotherapy targets. However, current inhibitors often lack selectivity, causing significant side effects. Understanding the precise electron transfer pathways could enable development of more specific interventions that disrupt cancer cell DNA synthesis while sparing healthy tissues. The hydrogen bond networks identified in this work represent potential new druggable sites. For longevity research, these findings contribute to our growing understanding of how cellular DNA repair and synthesis machinery functions at the molecular level, processes directly linked to aging and genomic stability.