Nitrogenase iron protein NifH / NifH/frxC family / NifH/chlL conserved site / 4Fe-4S iron sulfur cluster binding proteins, NifH/frxC family / NifH/frxC family signature 2. / NifH/frxC family signature 1. / NIFH_FRXC family profile. / Nitrogenase molybdenum-iron protein beta chain, N-terminal / Domain of unknown function (DUF3364) / Nitrogenase molybdenum-iron protein alpha chain ...Nitrogenase iron protein NifH / NifH/frxC family / NifH/chlL conserved site / 4Fe-4S iron sulfur cluster binding proteins, NifH/frxC family / NifH/frxC family signature 2. / NifH/frxC family signature 1. / NIFH_FRXC family profile. / Nitrogenase molybdenum-iron protein beta chain, N-terminal / Domain of unknown function (DUF3364) / Nitrogenase molybdenum-iron protein alpha chain / Nitrogenase molybdenum-iron protein beta chain / Nitrogenase component 1, alpha chain / Nitrogenase component 1, conserved site / Nitrogenases component 1 alpha and beta subunits signature 2. / Nitrogenases component 1 alpha and beta subunits signature 1. / Nitrogenase/oxidoreductase, component 1 / : / Nitrogenase component 1 type Oxidoreductase / 2Fe-2S ferredoxin, iron-sulphur binding site / 2Fe-2S ferredoxin-type iron-sulfur binding region signature. / 2Fe-2S iron-sulfur cluster binding domain / Beta-grasp domain superfamily / 2Fe-2S ferredoxin-type iron-sulfur binding domain profile. / 2Fe-2S ferredoxin-type iron-sulfur binding domain / 2Fe-2S ferredoxin-like superfamily / P-loop containing nucleoside triphosphate hydrolase 類似検索 - ドメイン・相同性
Nitrogenase iron protein 1 / Nitrogenase molybdenum-iron protein alpha chain / Nitrogenase molybdenum-iron protein beta chain / Protein FeSII 類似検索 - 構成要素
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
5R01GM148607-02
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
5R35GM138206
米国
Other private
Searle Scholars
引用
ジャーナル: Nature / 年: 2025 タイトル: Structural basis for the conformational protection of nitrogenase from O. 著者: Sarah M Narehood / Brian D Cook / Suppachai Srisantitham / Vanessa H Eng / Angela A Shiau / Kelly L McGuire / R David Britt / Mark A Herzik / F Akif Tezcan / 要旨: The low reduction potentials required for the reduction of dinitrogen (N) render metal-based nitrogen-fixation catalysts vulnerable to irreversible damage by dioxygen (O). Such O sensitivity ...The low reduction potentials required for the reduction of dinitrogen (N) render metal-based nitrogen-fixation catalysts vulnerable to irreversible damage by dioxygen (O). Such O sensitivity represents a major conundrum for the enzyme nitrogenase, as a large fraction of nitrogen-fixing organisms are either obligate aerobes or closely associated with O-respiring organisms to support the high energy demand of catalytic N reduction. To counter O damage to nitrogenase, diazotrophs use O scavengers, exploit compartmentalization or maintain high respiration rates to minimize intracellular O concentrations. A last line of damage control is provided by the 'conformational protection' mechanism, in which a [2Fe:2S] ferredoxin-family protein termed FeSII (ref. ) is activated under O stress to form an O-resistant complex with the nitrogenase component proteins. Despite previous insights, the molecular basis for the conformational O protection of nitrogenase and the mechanism of FeSII activation are not understood. Here we report the structural characterization of the Azotobacter vinelandii FeSII-nitrogenase complex by cryo-electron microscopy. Our studies reveal a core complex consisting of two molybdenum-iron proteins (MoFePs), two iron proteins (FePs) and one FeSII homodimer, which polymerize into extended filaments. In this three-protein complex, FeSII mediates an extensive network of interactions with MoFeP and FeP to position their iron-sulphur clusters in catalytically inactive but O-protected states. The architecture of the FeSII-nitrogenase complex is confirmed by solution studies, which further indicate that the activation of FeSII involves an oxidation-induced conformational change.