This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Microorganisms can do remarkable things—for example, nitrogen fixation, the conversion of nitrogen gas (N₂) into a form that organisms can use. Although nitrogen gas makes up around 78% of Earth's atmosphere, plants and animals cannot directly use it.
The two nitrogen atoms are held together by superglue: a chemical triple bond. But some microorganisms have a superpower: they can fix nitrogen by breaking these bonds and converting N₂ into ammonia, which can then be used to build biological molecules. One such superhero is the deep-sea archaeon Methanocaldococcus infernus.
This microorganism lives in marine volcanic areas, where temperatures of vent fluids can exceed the boiling point of water. That sparked the curiosity of scientists from Tristan Wagner's laboratory at the Max Planck Institute for Marine Microbiology in Bremen. They "tamed" this microorganism, forcing it to fix N2 even at temperatures above 90°C (194°F).
"How do they do it, in such heat? And how can the enzyme splitting the N2 triple bond work under these conditions?" Wagner asked. The enzyme that provides the superpower of fixing N2 is called nitrogenase, an enzyme that contains the most complex metallocofactor known in biology.
Metallocofactors are metallic helper molecules bound to an enzyme and essential for its function. The best-studied and best-performing nitrogenases have a metallocofactor containing molybdenum, but they also exist in vanadium- and iron-only forms. How these different forms are related to one another and exactly how their metal centers enable them to break the N₂ triple bond remains an active area of research.
"The nitrogenase found in Methanocaldococcus infernus is remarkable because it seems to share traits of the molybdenum, vanadium and iron forms. This type of nitrogenase could be similar to a common nitrogenase ancestor, the ancient system from which they all evolved. Thus, it could reveal common principles in the nitrogenase reaction," Wagner says.
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