Nitrogenase Archives

Schematic of methods used to insert ancestral genes into the host A. vinelandii genome -- Nature Communications

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Fossils & Paleontology, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, Press Release

Resurrecting Ancient Enzymes in NASA’s Search For Life Beyond Earth

by Keith CowingMarch 27, 2026March 27, 2026

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 […]

Betul Kacar presents samples in her lab Credit Photo by Jeff Miller/UW–Madison

Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, People Of Astrobiology, Press Release

Resurrected Ancient Enzyme Offers New Window Into Early Earth And The Search For Life Beyond It

by Keith CowingJanuary 23, 2026January 23, 2026

By resurrecting a 3.2-billion-year-old enzyme and studying it inside living microbes, researchers at the University of Wisconsin–Madison have created a new way to improve our understanding of the origins of […]

c. Approximate ages for the origin of nitrogenase isoforms are based on geochemical12 and phylogenetic data. -- biorxiv.org

Astrochemistry, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Resurrected Nitrogenases Recapitulate Canonical N-isotope Biosignatures Over Two Billion Years

by Keith CowingNovember 12, 2025June 10, 2026

Nitrogen isotope fractionation (ε15N) in sedimentary rocks has provided evidence for biological nitrogen fixation, and thus primary productivity, on the early Earth.

N-isotope fractionation values observed in this study compared to the sedimentary δ15N record a, and known ranges of extant microbial biomass b, The sedimentary database includes bulk rock δ15N (dark grey) and kerogen δ15N (light grey), from both marine and nonmarine rocks across a range of very low to moderate metamorphic grades22,39,40. The purple bar in a and b represents the average fractionation signature of all ancestors in this study and is largely coincident with the minimum d15N values seen in the rock record which are presumed to record nitrogen-fixation unaffected by subsequent nitrogen cycling. The partial range of bacterial and fractionation signatures are labeled as the modern range of N-isotopic values41 (see Figure S3 for extended range). -- biorxiv.org

Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Status Report

Persistent Nitrogenase Isotope Signatures Over Two Billion Years Of Engineered Evolution

by Keith CowingJune 28, 2025

Nitrogen isotope fractionation (ε15N) in sedimentary rocks has provided evidence for biological nitrogen fixation, and thus primary productivity, on the early Earth.

Overview of the methodological pipeline for massive protein structure prediction and experimental crystallographic analysis of extant and ancestral nitrogenase enzymes.

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, Status Report

Structural Evolution Of Nitrogenase Enzymes Over Geologic Time

by Keith CowingApril 12, 2025April 12, 2025

Life on Earth is more than 3.5 billion years old, nearly as old as the age of the planet. Over this vast expanse of time, life and its biomolecules adapted […]

A schematic illustrating habitability of physical spaces as a function of physical and chemical conditions

Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Status Report

Nitrogenase Structural Evolution Across Earth’s History

by Keith CowingDecember 27, 2024December 27, 2024

Life on Earth is more than 3.5 billion years old—nearly as old as the age of the planet. Over this vast expanse of time, life and its biomolecules adapted to […]

Evolution of the ATP/ADP-binding site in nitrogenase NifH. (A) Nitrogenase NifHDK protein phylogeny. Phylogenetic positions of ancestral (AncAK029) and extant A. vinelandii (“Extant A. vin”) nitrogenase variants discussed in the main text are highlighted by colored circles. (B) Protein sequence alignment of NifH ATPase signature motifs (labeled) (54) site index from A. vinelandii NifH. (C) Residue-level intermolecular interactions in the ADP-binding site of A. vinelandii NifH (PDB 1FP6). All displayed residues are conserved between AncAK029 and WT. Curved lines delineate residues with nonspecific interactions that shape the binding site. (D) Estimated age range of nitrogenase ancestors mapped to Earth’s environmental history. Nitrogenases hosted by heterocystous cyanobacteria provide a minimum age constraint based on oldest fossil evidence (60). Atmospheric oxygenation plot and relative marine metal abundances are from Lyons et al. (61). -- mBio

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Status Report

Ancient Nitrogenases Are ATP Dependent

by Keith CowingJune 20, 2024June 20, 2024

Life depends on a conserved set of chemical energy currencies that are relics of early biochemistry. One of these is ATP, a molecule that, when paired with a divalent metal […]

NifH2 cycle of Mo-nitrogenase. The NifH2 homodimer is shown in blue; it houses two nucleotide binding sites and a [4Fe-4S] redox active cluster. One catalytic half (NifDK) of the NifD2K2 heterotetramer is shown in yellow (K) and green (D); each catalytic half houses one [8Fe-7S] (Pcluster) and a [7Fe-9S-Mo-C-homocitrate] (FeMo-co) active site metallocluster. When NifH2 binds to NifDK an electron is transferred from the [4Fe-4S] cluster to FeMo-co mediated by P-cluster. NifH2 then hydrolyzes 2 ATP, dissociates with MgADP bound and an oxidized [4Fe4S] cluster. MgADP is then exchanged for MgATP and the [4Fe-4S] cluster is reduced, preparing NifH2 for binding and electron transfer. -- biorxiv.org

Biochemistry & Organic Chemistry, Biophysics, Genomics, Proteomics, Bioinformatics, Status Report

The Origins Of ATP Dependence In Biological Nitrogen Fixation

by Keith CowingFebruary 27, 2024February 27, 2024

Life depends on a conserved set of chemical energy currencies that are relics of early biochemistry. One of these is ATP, a molecule that, when paired with a divalent metal […]

Structure and genetics of the nitrogenase G-subunit. A) Left, crystallographic structure of the extant A. vinelandii Vnf nitrogenase complex (VnfH, PDB 6Q9336; VnfDGK, PDB 5N6Y22 ) containing the G-subunit (dark blue). The Anf nitrogenase is inferred to be comparable in its multimeric structure, binding FeFe-co instead of FeV-co. Right, crystallographic structure of the extant Nif nitrogenase complex (NifH, PDB 1M3437; NifDK, PDB 3U7Q38) lacking the G subunit. B) Secondary structure of the Vnf G-subunit. C) Arrangement of the Nif, Vnf, and Anf structural genes in A. vinelandii. Vnf/AnfG (dark blue) is located between Vnf/AnfD and Vnf/AnfK genes. -- biorxiv.org

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Microbiology & Virology, Plant Biology, Status Report

An Orphan Protein Drove The Ecological Expansion Of Nitrogen Fixation

by Keith CowingApril 10, 2023April 10, 2023

Nitrogenases have catalyzed biological nitrogen fixation for billions of years and revolutionized planet Earth by supplying essential nitrogen to the biosphere.