The enzyme in question is nitrogenase, the only biological catalyst known to convert atmospheric nitrogen (N₂) into ammonia (NH₃) — a chemical transformation that makes all life on Earth possible. Without nitrogenase, plants, animals, and every other living organism would be unable to access the nitrogen they need to build proteins and DNA. The researchers, led by Professor Betül Kaçar, used a technique called ancestral sequence reconstruction to trace the enzyme's evolutionary history back more than three billion years, then synthesized the ancient genetic code and inserted it into modern bacteria.
What makes this experiment remarkable is that the resurrected enzyme actually worked. When the team inserted the ancient nitrogenase gene into living E. coli cells, the bacteria began producing a functional enzyme that could fix nitrogen — just as it did billions of years ago. This is not a simulation or a computer model; it is a real, functioning protein from the Archean eon, operating inside a modern cell. The ancient enzyme was found to be less efficient than its modern descendants, but it was robust enough to sustain nitrogen fixation, suggesting that even the earliest versions of this enzyme were capable of supporting life.
The implications extend far beyond Earth. Scientists have long debated how to distinguish biological signatures from non-biological processes when searching for life on Mars, Europa, or exoplanets. The nitrogen cycle produces a distinctive isotopic fingerprint — a specific ratio of nitrogen-14 to nitrogen-15 — that scientists have used as a biosignature for decades. But until now, no one knew whether the earliest, most primitive nitrogenases produced the same fingerprint as modern enzymes. The resurrected enzyme allowed the team to answer this question directly: the ancient nitrogenase produces a subtly different isotopic signature than modern versions, shifting the baseline for how scientists interpret nitrogen isotope data from rocks and meteorites.
This matters because the oldest rocks on Earth are scarce and heavily altered. When geologists find nitrogen isotope ratios in 3.5-billion-year-old rocks, they need to know whether those ratios indicate biological activity or geological processes. The resurrected enzyme provides a direct experimental reference point, rather than relying on assumptions. The same logic applies to Mars — the Perseverance rover is collecting samples that may contain ancient nitrogen signatures, and knowing what to look for could make the difference between detecting or missing the first evidence of extraterrestrial life.