OBERLIN, Ohio — The age-old quest to uncover the origins of life has been a longstanding challenge for scientists. Despite significant advancements, the genesis of life remains one of the grand enigmas of science. However, scientists at Oberlin College have outlined a new strategy for understanding the origin of life — electron transport chains.
“The most basic features of biology, that organisms are made of cells, that they pass genetic information through DNA, that they use protein enzymes to run their metabolism, all emerged through specific processes in very early evolutionary history,” says Aaron Goldman, an associate professor of biology at Oberlin College, in a media release. “Understanding how these most basic biological systems first took shape will not only give us greater insight into how life works at the most fundamental level, but what life actually is in the first place and how we might look for it beyond Earth.”
Researchers have traditionally used two distinct approaches to decipher how life commenced:
1. Bottom-Up Approach: This involves simulating early Earth conditions in laboratories to observe chemistries that could produce biomolecules and reactions observed in present-day organisms. While these “prebiotic chemistry” experiments paint potential scenarios of life’s inception, they don’t solidify how life genuinely originated.
2. Top-Down Approach: This method borrows techniques from evolutionary biology to estimate the appearance and nature of early life forms by analyzing present-day life data. Its limitation, though, is that it can only be traced back to the oldest conserved genes, not to the actual dawn of life.
While each method has its constraints, their combined results should ideally point towards the same conditions under which life emerged. The new study zeroes in on a biological phenomenon shared by a multitude of organisms: electron transport chains. These are crucial metabolic systems utilized by a myriad of life forms, from bacteria to humans, to convert energy into usable forms. While various life forms have specialized electron transport chains tailored to their energy needs, the researchers believe that this metabolic mechanism was likely harnessed by the very first life forms.
The team provides models for ancestral electron transport chains that could be traced back to life’s earliest evolutionary stages. They also discuss evidence suggesting that, even before life as we recognize it, electron transport chain-like chemistries might have been possible through interactions with minerals and primordial Earth waters.
This research is a pivotal culmination of a five-year endeavor by an interdisciplinary team. This endeavor explored topics such as electron transport chain reactions instigated by minerals and ancient enzymes’ interaction with prebiotic chemistry.
“The emergence of metabolism is an interdisciplinary question and so we need an interdisciplinary team to study this,” says Laurie Barge, a research scientist in astrobiology at NASA’s Jet Propulsion Laboratory. “Our work has utilized techniques from chemistry, geology, biology, and computational modeling, to combine these top-down and bottom-up approaches, and this kind of collaboration will be important for future studies of prebiotic metabolic pathways.”
The study is published in the journal Proceedings of the National Academy of Sciences.
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