biostudies-literatureAppia-Ayme CRoyal SocietyUK Research and InnovationBiotechnology and Biological Sciences Research Council105-124https://www.ebi.ac.uk/biostudies/studies/S-EPMC9542535biostudies-literatureUnknown118(1-2)All diazotrophic bacteria and archaea isolated so far utilise a nitrogenase enzyme-containing molybdenum in the active site co-factor to fix atmospheric dinitrogen to ammonia. However, in addition to the Mo-dependent nitrogenase, some nitrogen-fixing prokaryotes also express genetically distinct alternative nitrogenase isoenzymes, namely the V-dependent and Fe-only nitrogenases, respectively. Nitrogenase isoenzymes are expressed hierarchically according to metal availability and catalytic efficiency. In proteobacteria, this hierarchy is maintained via stringent transcriptional regulation of gene clusters by dedicated bacterial enhancer-binding proteins (bEBPs). The model diazotroph Azotobacter vinelandii contains two paralogs of the vanadium nitrogenase activator VnfA (henceforth, VnfA1), Molecular microbiologyInteractions between paralogous bacterial enhancer-binding proteins enable metal-dependent regulation of alternative nitrogenases in Azotobacter vinelandii.PMC9542535BBS/E/J/000PR9797ICA\R1\180088BB/N013476/1BB/W009986/1de Oliveira Martins CBueno Batista MChandra GLittle RDixon RAppia-Ayme CfalseInteractions between paralogous bacterial enhancer-binding proteins enable metal-dependent regulation of alternative nitrogenases in Azotobacter vinelandii.All diazotrophic bacteria and archaea isolated so far utilise a nitrogenase enzyme-containing molybdenum in the active site co-factor to fix atmospheric dinitrogen to ammonia. However, in addition to the Mo-dependent nitrogenase, some nitrogen-fixing prokaryotes also express genetically distinct alternative nitrogenase isoenzymes, namely the V-dependent and Fe-only nitrogenases, respectively. Nitrogenase isoenzymes are expressed hierarchically according to metal availability and catalytic efficiency. In proteobacteria, this hierarchy is maintained via stringent transcriptional regulation of gene clusters by dedicated bacterial enhancer-binding proteins (bEBPs). The model diazotroph Azotobacter vinelandii contains two paralogs of the vanadium nitrogenase activator VnfA (henceforth, VnfA1), 2022-01-01T00:00:00Z2022 Jul2025-04-04T09:29:36.153Z2025-04-04T09:29:36.153ZS-EPMC95425353571893610.1111/mmi.14955