Despite advances over the years, the origin of life remains one of science’s most enduring mysteries.
“The most basic characteristic of biology is that living things are made up of cells, and cells transmit genetic information. DNA, that they use protein enzymes to carry out their metabolism, all emerged through specific processes very early in their evolutionary history,” said Aaron Goldman, an associate professor of biology at Oberlin College. say. “Understanding how these most basic biological systems were first formed can only give greater insight into how life functions at its most basic level. It will give us a deeper insight into what life really is, and how we can look for life beyond Earth.”
The question of how life first appeared is usually a laboratory search for chemistries that can simulate the early Earth environment and create the same kinds of biomolecules and metabolic reactions that are found in living organisms today. studied through experimentation. This is known as a “bottom-up” approach because it deals with materials that would have existed on prebiotic Earth.
These so-called “prebiotic chemistry” experiments have successfully demonstrated how life occurs. there may be There are origins, but they can’t tell us how life actually happens did originated from On the other hand, there are also studies that use evolutionary biology techniques to reconstruct what early life forms looked like based on data from modern life forms. This is known as the ‘top-down’ approach and allows us to learn about the history of life on Earth.
However, top-down research cannot trace back to the origin of life, as it can only trace back to the time when genes were preserved in living organisms. Despite their limitations, top-down and bottom-up studies aim at the common goal of discovering the origin of life, and ideally the answers should converge on common ground.
Goldman, new article published by Laurie Barge, a space biology research scientist NASAJet Propulsion Laboratory (JPL)) et al., attempt to fill this methodological gap. By combining bottom-up laboratory studies of plausible pathways to the origin of life with top-down evolutionary reconstructions of early life forms, the authors show how life actually originated on early Earth. claims to be able to discover
In their paper, the authors describe a phenomenon central to life today: the electron transport chain, which can be studied by combining both bottom-up and top-down studies.
Electron transport chains are a type of metabolic system used to generate usable forms of chemical energy by organisms throughout the tree of life, from bacteria to humans. Many different types of electron transport chains are specialized for each life form and the energy metabolism they use. For example, our mitochondria contain electron transport chains associated with heterotrophic (food consuming) energy metabolism. Plants, on the other hand, have a completely different electron transport system: photosynthesis (Generation of energy from sunlight).
And throughout the microbial world, organisms use a wide range of electron transport chains associated with a variety of different energy metabolisms. However, despite these differences, the authors describe evidence from top-down studies showing that this type of metabolic strategy was used by the earliest life forms, and very early in evolutionary history. We present several models of possible ancestral electron transport chains.
They also suggest that chemistry like electron transport chains may have been facilitated by minerals and early Earth ocean waters, even before the emergence of life as we know it. I researched the evidence. Inspired by these observations, the authors suggest future studies that integrate top-down and bottom-up studies on the earliest history of electron transport systems for a broader understanding of ancient energy metabolism and the origin of life. Strategy is outlined.
The study is the culmination of five years of research by this interdisciplinary team of institutions led by JPL’s Burge. The team is funded by the NASA-NSF Ideas Lab for the Origin of Life to study how metabolic reactions occur in the geological environment. on early Earth. Previous work by the team, for example, has explored specific electron transport chain reactions (led by JPL researcher Jessica Weber) triggered by minerals.how ancient enzyme there may be Incorporates prebiotic chemistry into the active site (Led by Goldman).and Microbial Metabolism in Extremely Energy-Limited Environments (led by Doug LaRow of the University of Southern California).
“The emergence of metabolism is a multidisciplinary problem, so we need a multidisciplinary team to study it,” says Barge. “Our research has combined top-down and bottom-up approaches, utilizing techniques from chemistry, geology, biology and computational modeling. It will be important for future research.”
Reference: “Electron Transport Chain as a Window to Early Stages of Evolution,” Aaron D. Goldman, Jessica M. Webber, Douglas E. LaRow, and Laura M. Burge, 14 Aug. 2023, Available here. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2210924120
This research was funded by the National Aeronautics and Space Administration.