NASA Revives Ancient Enzymes to Hunt Extraterrestrial Life

Resurrected 3.2-billion-year-old enzyme validates key biosignature for ancient life on Earth and beyond

Jan. 30, 2026 at 8:55pm

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NASA-supported scientists have resurrected an enzyme first used by organisms on Earth 3.2-billion years ago and, in the process, have validated a chemical biosignature in rocks that is used to understand ancient life on Earth. The research provides a new understanding of what Earth's biosphere was like early in our planet's history and confirms a reliable biosignature that could be used by robotic or human explorers to look for signs of ancient life on other worlds.

Why it matters

Nitrogen fixation is critical for life as we know it, so understanding the history and evolution of the nitrogenase enzyme that enables this process is key to deciphering the origins of life on Earth and potentially identifying signs of ancient life on other planets. Validating the use of nitrogen isotopes as a reliable biosignature can help guide future astrobiological exploration.

The details

The study focused on the enzyme nitrogenase, which allows a select group of organisms called diazotrophs to convert unusable atmospheric nitrogen into biologically useful forms. By reverse-engineering modern nitrogenase to reveal simpler ancestral versions, the researchers found that the nitrogen isotope signatures produced by these ancient enzymes are consistent with those found in the geological record, confirming their reliability as a biosignature for ancient life.

  • The research was published in Nature Communications on January 22, 2026.
  • The nitrogenase enzyme first evolved 3.2 billion years ago, when only single-celled microorganisms existed on Earth.

The players

Betül Kaçar

Leads the Kaçar Lab at the University of Wisconsin-Madison and is working to understand the history of life at a planetary scale and the potential for life in the universe by rebuilding extinct biochemistries used by ancient organisms.

Holly Rucker

A doctoral candidate in the Kaçar Lab and lead author on the paper, who examined the behaviors of older versions of the nitrogenase enzyme when inserted into living microbes.

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What they’re saying

“Early life on Earth operated under conditions so different from today that it may have appeared almost alien.”

— Betül Kaçar, Lab Director (Nature Communications)

“As you step back in time, the DNA sequences of these ancient nitrogenases are very different than modern nitrogenases. We also see that the enzyme structure varies with age. Yet we find that despite these sequence and structure-level differences, these ancient enzymes still do the same chemistry as their modern descendants.”

— Holly Rucker, Doctoral Candidate (Nature Communications)

What’s next

The collection of synthetic genes created by the team represents different versions of nitrogenase that would have existed over a span of two billion years of evolutionary history, which can help fill in gaps of knowledge about how the enzyme has changed over time and what ancient nitrogen fixers were like.

The takeaway

This research validates the use of nitrogen isotopes as a reliable biosignature for ancient life on Earth, which could be a powerful tool for identifying signs of past life on other planets. Understanding the evolution of critical metabolic enzymes like nitrogenase provides insights into the origins of life and the potential for life beyond our planet.