Proton Pairs Swap Strands in Double Helix to Make Mutations

On Wednesday 16 August 2023 at the American Chemical Society (ACS) meeting in a session organized by the Division of Biological Chemistry, Science Synergy Chair of Science Noah Bray-Ali will give a talk on the way life changes. Seventy years ago the discovery of the double helix structure of DNA suggested a way for life to change and scientists have struggled since then to make it work. In April 2023 our scientists announced the discovery of the mechanism for spontaneous mutation.

**Spontaneous Mutation in DNA-**The code of life comes in pairs of protons H that bind the two strands of the double helix of deoxyribonucleic acid (DNA). To use the code to live life and to make new life, these bonds must break. For every ten billion pairs of bonds that break, two bond pairs will spontaneously mutate by swapping which side of the gap the proton pairs sit. Adapted with permission from J. D. Watson and F. H. C. Crick, “The Structure of DNA,” Cold Spring Harb. Symp. Quant. Bio. 18, 123 (1953). Copyright Cold Spring Harbor Laboratory Press.

Why does life change? Each breath breaks the bonds between base pairs that bind the double helix and that store the code of life. Each generation breaks these bonds to pass the code of life on to the next generation.

Pairs of particles known as protons which form the nucleus of the atoms of hydrogen, the lightest chemical element, swap sides within the bonds between base pairs in DNA at a rate of five hundred million swaps each second. Yet the bonds break at a rate two million times faster than the proton pairs swap sides. The sudden split forces the proton pair to choose sides at random: A small fraction of the time, twice for every ten billion bond pairs that break, the proton pair lands in a rare form that restores the symmetry between the sense strand and its complement, destroying genetic information, and driving life to change.