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-Structure paper
Title | Structural consequences of turnover-induced homocitrate loss in nitrogenase. |
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Journal, issue, pages | Nat Commun, Vol. 14, Issue 1, Page 1091, Year 2023 |
Publish date | Feb 25, 2023 |
![]() | Rebeccah A Warmack / Ailiena O Maggiolo / Andres Orta / Belinda B Wenke / James B Howard / Douglas C Rees / ![]() |
PubMed Abstract | Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The active site FeMo-cofactor ...Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The active site FeMo-cofactor contains a [7Fe:1Mo:9S:1C] metallocluster coordinated with an R-homocitrate (HCA) molecule. Here, we establish through single particle cryoEM and chemical analysis of two forms of the Azotobacter vinelandii MoFe-protein - a high pH turnover inactivated species and a ∆NifV variant that cannot synthesize HCA - that loss of HCA is coupled to α-subunit domain and FeMo-cofactor disordering, and formation of a histidine coordination site. We further find a population of the ∆NifV variant complexed to an endogenous protein identified through structural and proteomic approaches as the uncharacterized protein NafT. Recognition by endogenous NafT demonstrates the physiological relevance of the HCA-compromised form, perhaps for cofactor insertion or repair. Our results point towards a dynamic active site in which HCA plays a role in enabling nitrogenase catalysis by facilitating activation of the FeMo-cofactor from a relatively stable form to a state capable of reducing dinitrogen under ambient conditions. |
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Methods | EM (single particle) |
Resolution | 1.92 - 2.71 Å |
Structure data | EMDB-26957, PDB-8crs: EMDB-27316, PDB-8dbx: EMDB-28272, PDB-8enl: EMDB-28273, PDB-8enm: EMDB-28274, PDB-8enn: EMDB-28275, PDB-8eno: |
Chemicals | ![]() ChemComp-ICS: ![]() ChemComp-HCA: ![]() ChemComp-1N7: ![]() ChemComp-CLF: ![]() ChemComp-FE: ![]() ChemComp-HOH: ![]() ChemComp-1CL: ![]() ChemComp-UNX: ![]() ChemComp-CIT: |
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![]() | METAL BINDING PROTEIN / ![]() ![]() ![]() ![]() ![]() |