Temperature-Dependent N2 Reduction and Energy Demands of Mo- and V-Nitrogenases
Year: 2026
Type: article
Abstract: Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia, a key step in the global nitrogen cycle. The Mo-and V-dependent nitrogenase isozymes are expressed under different environmental conditions, including temperature. Yet very little is known about how the product profiles and energy (ATP) requirements for these isozymes change with temperature. Here, we examine the temperature dependence of total electron flux, electron partitioning into the products NH3 and H2, and ATP energy costs per N2 fixed for purified Mo-and V-nitrogenases from Azotobacter vinelandii over a 10-50 ˚C temperature range. Both isozymes exhibit similar temperature-dependent scaling of total electron flux to all products across the temperature range, but with significantly different distributions of electrons to H2 or NH3 formation. As temperature increases, V-nitrogenase diverts an increasing fraction of electron flux into H2 formation, whereas Mo-nitrogenase maintains a nearly constant electron partitioning to N2 reduction. The ATP molecules hydrolyzed per N2 reduced change little for the Mo-nitrogenase across this temperature range, but rises significantly for the V-nitrogenase with increasing temperature, reaching over 200 ATP per N2 fixed at 50 ˚C. These results demonstrate that, in A. vinelandii, the Mo-and V-nitrogenases exhibit significantly different responses of electron partitioning to products and ATP hydrolyzed per N2 reduced across the temperature range. These findings suggest environmental conditions under which each isozyme would be optimal, with V-and Monitrogenase both being favorable at low temperatures and Mo-nitrogenase being the only energetically reasonable enzyme at higher temperatures.
Source: Journal of Biological Chemistry
Institutions: Utah State University, University of Wisconsin–Madison
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,430
Awards: RECENT THEORETICAL WORK SUGGESTS THAT AN EARLY STEP IN THE ORIGIN OF LIFE WAS THE EMERGENCE OF ENSEMBLES OF CHEMICALS THAT INTERACTED WITH ONE ANOTHER TO COLLECTIVELY PROPAGATE: IN THE PRESENCE OF REPLENISHING INPUTS OF CHEMICAL PRECURSORS (FOOD) AND ENERGY ALL CHEMICALS IN THE ENSEMBLE ARE PRODUCED BY THE ACTIONS OF OTHER CHEMICALS IN THE ENSEMBLE. FURTHERMORE ADVANCES IN EVOLUTIONARY THEORY SUGGEST THAT IF THESE INTERACTING MOLECULAR ENSEMBLES WERE SPATIALLY STRUCTURED FOR EXAMPLE BY BEING ADSORBED ONTO THE SURFACES OF SUBMERGED MINERALS THEY WOULD BE LIKELY TO EVOLVE ADAPTIVELY. SPECIFICALLY A PROCESS CALLED NEIGHBORHOOD SELECTION WOULD TEND TO ENRICH FOR ENSEMBLES WITH PROGRESSIVELY IMPROVED ABILITIES TO COLONIZE NEW MINERAL GRAINS. SINCE THE ABILITY TO PROPAGATE (GROW) AND EVOLVE ADAPTIVELY ARE TWO KEY FEATURES OF LIFE ANY ENSEMBLE HAVING THESE PROPERTIES WOULD BE LIFE-LIKE EVEN IF IT WERE NOT ORGANIZED INTO CELL-LIKE COMPARTMENTS AND LACKED ANY DIGITAL GENETIC ENCODING. THE PROPOSED RESEARCH WILL USE THEORY AND LABORATORY EXPERIMENT TO BETTER UNDERSTAND THE ORIGIN AND EVOLUTION OF SURFACE-ASSOCIATED LIFE-LIKE INTERACTING MOLECULAR ENSEMBLES (SLIMES). GUIDED BY ARTIFICIAL ECOSYSTEM SELECTION A METHOD USED IN MICROBIAL ECOLOGY WE WILL EXPLORE THE BEHAVIOR OF SETS OF CHEMICALS ASSOCIATED WITH MINERAL GRAINS TO SEE IF THEY ARE CAPABLE OF RESPONDING TO AN ARTIFICIAL SELECTION PRESSURE., G7941627367
OpenAlex ID: W7223156904