The conformational changes induced by ubiquinone binding in the Na+-pumping NADH:ubiquinone oxidoreductase (Na+-NQR) are kinetically controlled by conserved glycines 140 and 141 of the NqrB subunit
| Autor: | Madeleine Strickland, Oscar Juárez, Darcie Cook, Petra Hellwig, Yashvin Neehaul, Blanca Barquera |
|---|---|
| Přispěvatelé: | Chimie de la matière complexe (CMC), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Conformational change
Protein Conformation Ubiquinone Stereochemistry Électrochimie Glycine Respiratory chain Spectroscopie Bioenergetics Biochemistry Cofactor Oxidoreductase Spectroscopy Fourier Transform Infrared Molecular Biology Conserved Sequence DNA Primers chemistry.chemical_classification Ubiquinone binding Electron Transport Complex I Base Sequence biology Chemistry Spectroélectrochimie Cell Biology [CHIM.CATA]Chemical Sciences/Catalysis Electron transport chain Respiratory enzyme Chimie Physique Kinetics biology.protein Sodium-Potassium-Exchanging ATPase Protein Binding |
| Zdroj: | The Journal of biological chemistry The Journal of biological chemistry, 2014, 289 (34), pp.23723-23733. ⟨10.1074/jbc.M114.574640⟩ |
| ISSN: | 1083-351X |
| DOI: | 10.1074/jbc.M114.574640⟩ |
| Popis: | PMID: 25006248 PMCID: PMC4156058; Na(+)-pumping NADH:ubiquinone oxidoreductase (Na(+)-NQR) is responsible for maintaining a sodium gradient across the inner bacterial membrane. This respiratory enzyme, which couples sodium pumping to the electron transfer between NADH and ubiquinone, is not present in eukaryotes and as such could be a target for antibiotics. In this paper it is shown that the site of ubiquinone reduction is conformationally coupled to the NqrB subunit, which also hosts the final cofactor in the electron transport chain, riboflavin. Previous work showed that mutations in conserved NqrB glycine residues 140 and 141 affect ubiquinone reduction and the proper functioning of the sodium pump. Surprisingly, these mutants did not affect the dissociation constant of ubiquinone or its analog HQNO (2-n-heptyl-4-hydroxyquinoline N-oxide) from Na(+)-NQR, which indicates that these residues do not participate directly in the ubiquinone binding site but probably control its accessibility. Indeed, redox-induced difference spectroscopy showed that these mutations prevented the conformational change involved in ubiquinone binding but did not modify the signals corresponding to bound ubiquinone. Moreover, data are presented that demonstrate the NqrA subunit is able to bind ubiquinone but with a low non-catalytically relevant affinity. It is also suggested that Na(+)-NQR contains a single catalytic ubiquinone binding site and a second site that can bind ubiquinone but is not active. |
| Databáze: | OpenAIRE |
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