Title: New Research Looks to Electron Transport Chains as Clue to Origin of Life
Subtitle: Bridging “bottom-up” and “top-down” methodologies offers insights into ancient metabolic strategies
Date: August 14, 2023
The mystery of how life emerged on Earth has long puzzled scientists, but a recent interdisciplinary article published in the Proceedings of the National Academy of Sciences suggests a potential breakthrough. Researchers propose bridging the “bottom-up” and “top-down” approaches to studying life’s origins by focusing on electron transport chains, a universal metabolic system.
For years, scientists have used laboratory experiments to simulate early Earth environments in search of chemistries that could create biomolecules and metabolic reactions observed in organisms today. These “bottom-up” methods have shed light on how life may have originated, but not how it actually did.
On the other hand, “top-down” research utilizes techniques from evolutionary biology to reconstruct early life forms based on the data from present-day organisms. However, this approach can only trace back to the emergence of genes that are still conserved today, limiting its ability to delve into the origins of life.
To bridge this methodological gap, Aaron Goldman, Associate Professor of Biology at Oberlin College, Laurie Barge, Research Scientist in Astrobiology at NASA’s Jet Propulsion Laboratory (JPL), and their colleagues propose combining bottom-up laboratory research with top-down evolutionary reconstructions. They argue that studying electron transport chains, a fundamental aspect of life today, can provide insights into how life truly originated on early Earth.
Electron transport chains are metabolic systems used by organisms across the tree of life to produce usable forms of chemical energy. Despite the variations across different life forms, evidence from top-down research suggests that this metabolic strategy was employed by the earliest life forms. The authors present several models for ancestral electron transport chains that could date back to very early evolutionary history.
Furthermore, the researchers highlight bottom-up evidence indicating that minerals and early Earth ocean water could have facilitated electron transport chain-like chemistry even before the emergence of life as we know it. Inspired by these findings, the authors propose future research strategies that integrate both top-down and bottom-up approaches to gain a better understanding of ancient energy metabolism and the origin of life.
The recent article is the culmination of five years of interdisciplinary work led by Laurie Barge at NASA’s JPL. The team, funded by the NASA-NSF Ideas Lab for the Origins of Life, has explored various aspects of prebiotic metabolic reactions and their geological settings on early Earth. Their previous studies have delved into specific electron transport chain reactions driven by minerals, the incorporation of prebiotic chemistry in ancient enzymes, and microbial metabolism in energy-limited environments.
“The emergence of metabolism is an interdisciplinary question, and so we need an interdisciplinary team to study this,” says Barge. Their collaborative approach, combining techniques from chemistry, geology, biology, and computational modeling, is expected to play a crucial role in future studies of prebiotic metabolic pathways.
This groundbreaking research opens up new avenues for understanding how life first emerged on Earth. By examining electron transport chains, scientists may be one step closer to unravelling the enigma of life’s origins and gaining valuable insights into the nature of life itself, both on Earth and beyond.
Reference:
“Electron transport chains as a window into the earliest stages of evolution” by Aaron D. Goldman, Jessica M. Weber, Douglas E. LaRowe, and Laura M. Barge, Proceedings of the National Academy of Sciences, August 14, 2023.
DOI: 10.1073/pnas.2210924120