Understanding the P-Cluster of Vanadium Nitrogenase: an EPR and XAS Study of the Holo vs. Apo Forms of the Enzyme.

Autor: Wahl IM; Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, Mülheim an der Ruhr, 45470, Germany., Sengupta K; Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, Mülheim an der Ruhr, 45470, Germany., van Gastel M; Department of Molecular Theory and Spectroscopy, Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhem-Platz 1, Mülheim an der Ruhr, 45470, Germany., Decamps L; Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, Mülheim an der Ruhr, 45470, Germany., DeBeer S; Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, Mülheim an der Ruhr, 45470, Germany.
Jazyk: angličtina
Zdroj: Chembiochem : a European journal of chemical biology [Chembiochem] 2024 Nov 15, pp. e202400833. Date of Electronic Publication: 2024 Nov 15.
DOI: 10.1002/cbic.202400833
Abstrakt: The catalytic moiety of nitrogenases contains two complex metalloclusters: The M-cluster (also called cofactor), where the catalytic reduction of substrates takes place, and the [Fe 8 S 7 ] P-cluster responsible for electron transfer. Due to discrepancies between crystallography and EPR spectroscopy, the exact structure of the P-cluster in the VFe protein remains a topic of debate. Herein, we use an apo-form of VFe (which retains the P-cluster but lacks the FeVco) to study the VFe P-cluster. SDS-PAGE and NativePAGE showed a heterogeneous composition of the VFe and the apo-VFe samples with the presence of α 1 β 2 δ 2 and α 1 β 2 complexes. The parallel mode EPR measurements of IDS oxidized MoFe, apo-MoFe, and VFe samples reveal a signal at g=12 associated with the two-electron oxidized state of the P-cluster (P 2+ ) for all three samples, albeit with different intensities. In contrast, no P 2+ was observed for IDS oxidized apo-VFe. Additionally, comparisons between apo-MoFe, apo-VFe and the model complex (NBu 4 ) 2 [Fe 4 S 4 (SPh) 4 ] via EXAFS measurements showed that apo-VFe does not contain a fully formed [Fe 8 S 7 ] P-cluster, but rather is comprised of fragmented iron-sulfur clusters. Our results point to a possible variation in the structure of the P-cluster in the different forms of the nitrogenase.
(© 2024 The Author(s). ChemBioChem published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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