EAGER: Defining the Role of UV light in Prebiotic Chemical Evolution: the Imidazolium Bridge in Non-enzymatic RNA Replication

Harvard University, Cambridge MA

Investigators

Abstract

If life began on Earth when chemistry led to the molecular building blocks, which in turn self-assembled to form cells, then this prebiotic chemistry must have been a natural extension of the environmental conditions somewhere on the planet. Mid-range UV light (UVC) was one such robust environmental factor on the surface of early Earth. Were the legacy photoproperties of the molecular building blocks of today's life shaped by UVC fluxes and UVC photochemistry? How could we prove that? The PI will be able for the first time to answer unambiguously a long-standing central question in the origins of life field, regarding the role of UV light. The PI's experimental database - in particular, elucidating the mechanisms of RNA and DNA self-repair, will be invaluable to a much broader audience of scientists from basic biophysics to translational medicine. Students and postdoctoral researchers, including members of underrepresented groups in STEM, will receive training in technology and scientific applications at the intersection of chemistry, physics, and planetary science. The PI will communicate our findings to the general public. The question of how prebiotic chemistry, on early Earth or other planetary bodies, led to the emergence of life remains wide open. In this project the PI will focus on resolving the mechanisms for non-enzymatic self-replication of RNA. This is the defining step in the transition from prebiotic synthetic chemistry to the self-assembly of evolving protocells for surficial origins of life scenarios based on RNA. The PI will purchase mid-infrared femtosecond transient absorption spectrophotometer, complemented by an FTIR spectrometer to characterize samples stationary before and after transient measurements. The IR spectrophotometer will be integrated into the PI's operational UV-VIS femtosecond pump-probe system with a tunable excitation range starting at 190 nm. The current UV-VIS system has allowed the PI to study the photodynamics of some monomers (e.g., nucleotides), the selectivity of their synthetic pathways, and related photoredox cycles. However, the important steps of oligomerization, and many of the precursors, like the imidazolium bridge in RNA self- replication, have viable spectroscopic signatures only in the IR. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.