biostudies-literatureChanderban MU.S. Department of EnergyArkansas Biosciences InstituteNational Science Foundatione0103323https://www.ebi.ac.uk/biostudies/studies/S-EPMC10537573biostudies-literatureUnknown89(9)All nitrogen-fixing bacteria and archaea (diazotrophs) use molybdenum (Mo) nitrogenase to reduce dinitrogen (N₂) to ammonia, with some also containing vanadium (V) and iron-only (Fe) nitrogenases that lack Mo. Among diazotrophs, the regulation and usage of the alternative V-nitrogenase and Fe-nitrogenase in methanogens are largely unknown. <i>Methanosarcina acetivorans</i> contains <i>nif</i>, <i>vnf</i>, and <i>anf</i> gene clusters encoding putative Mo-nitrogenase, V-nitrogenase, and Fe-nitrogenase, respectively. This study investigated nitrogenase expression and growth by <i>M. acetivorans</i> in response to fixed nitrogen, Mo/V availability, and CRISPRi repression of the <i>nif</i>, <i>vnf</i>, and/or <i>anf</i> gene clusters. The availability of Mo and V significantly affecApplied and environmental microbiologyExpression of V-nitrogenase and Fe-nitrogenase in <i>Methanosarcina acetivorans</i> is controlled by molybdenum, fixed nitrogen, and the expression of Mo-nitrogenase.PMC105375731842401MCB1817819DE-SC0019226Chanderban MDhamad AEHill CALessner DJfalseExpression of V-nitrogenase and Fe-nitrogenase in <i>Methanosarcina acetivorans</i> is controlled by molybdenum, fixed nitrogen, and the expression of Mo-nitrogenase.All nitrogen-fixing bacteria and archaea (diazotrophs) use molybdenum (Mo) nitrogenase to reduce dinitrogen (N₂) to ammonia, with some also containing vanadium (V) and iron-only (Fe) nitrogenases that lack Mo. Among diazotrophs, the regulation and usage of the alternative V-nitrogenase and Fe-nitrogenase in methanogens are largely unknown. <i>Methanosarcina acetivorans</i> contains <i>nif</i>, <i>vnf</i>, and <i>anf</i> gene clusters encoding putative Mo-nitrogenase, V-nitrogenase, and Fe-nitrogenase, respectively. This study investigated nitrogenase expression and growth by <i>M. acetivorans</i> in response to fixed nitrogen, Mo/V availability, and CRISPRi repression of the <i>nif</i>, <i>vnf</i>, and/or <i>anf</i> gene clusters. The availability of Mo and V significantly affec2023-01-01T00:00:00Z2023 Sep2025-04-26T15:07:31.393Z2025-04-06T14:48:26.902ZS-EPMC105375733769504310.1128/aem.01033-23