A groundbreaking research team from the University of Wisconsin-Madison has successfully reverse-engineered a primitive nitrogen-fixing enzyme. This discovery sheds light on how life thrived before the Earth was transformed by oxygen and establishes reliable chemical markers for detecting extraterrestrial life.
Resurrection and characterization of an ancestral nitrogenase. Image credit: Rucker et al., doi: 10.1038/s41467-025-67423-y.
Led by Professor Betül Kaçar, the research focuses on an essential enzyme known as nitrogenase, which plays a pivotal role in converting atmospheric nitrogen into bioavailable forms.
“We selected an enzyme that significantly influences life on Earth and investigated its evolutionary history,” Professor Kaçar stated.
“Without nitrogenase, the existence of modern life as we know it would be impossible.”
Traditionally, scientists have depended on geological evidence to reconstruct Earth’s historical life.
However, significant fossils and rock samples are scarce and often require fortuitous discovery.
Professor Kaçar and his team view synthetic biology as a valuable tool to bridge these gaps, allowing them to construct specific ancient enzyme reconstructions, insert these into microorganisms, and study them in contemporary lab settings.
“The Earth of 3 billion years ago was vastly different from the world we recognize today,” remarked Dr. Holly Rucker.
“Before the Great Oxidation Event, the atmosphere was rich in carbon dioxide and methane, and life predominantly consisted of anaerobic microorganisms.”
“Understanding how these microorganisms accessed vital nutrients like nitrogen enhances our comprehension of how life persisted and evolved before oxygen-dependent organisms began to alter the planet.”
“Though fossilized enzymes are unavailable for study, these enzymes can leave discernible isotopic traces, measurable in rock samples.”
“Much of the prior research assumed ancient enzymes produced isotopic signatures akin to modern enzymes,” added Dr. Rucker.
“This holds true for nitrogenase; the isotopic traces we observe from ancient times correspond with modern signatures, providing deeper insights into the enzyme itself.”
The researchers discovered that ancient nitrogenase enzymes, despite having different DNA sequences, maintain the same mechanisms for isotopic signatures observed in the rock record.
“As astrobiologists, our understanding of Earth helps us comprehend the potential for life elsewhere in the universe,” Professor Kaçar emphasized.
“The quest for life begins right here on our 4-billion-year-old planet.”
“To grasp future possibilities and life beyond our planet, we must first understand our own history.”
The results were published today in the online journal Nature Communications, accessible here.
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Rucker et al. 2026. The revived nitrogenase reproduces the standard N isotope biosignature spanning two billion years. Nat Commun 17,616; doi: 10.1038/s41467-025-67423-y
Source: www.sci.news
