[NMR paper] Electron Transfer Mechanism of the Rieske Protein from Thermus thermophilus from Solution NMR investigations.

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Electron Transfer Mechanism of the Rieske Protein from Thermus thermophilus from Solution NMR investigations.

Related Articles Electron Transfer Mechanism of the Rieske Protein from Thermus thermophilus from Solution NMR investigations.

Biochemistry. 2013 Mar 12;

Authors: Hsueh KL, Tonelli M, Cai K, Westler WM, Markley JL

Abstract
We report NMR data indicating that the Rieske protein from the cytochrome bc complex of Thermus thermophilus (TtRp) undergoes modest redox-state-dependent and ligand-dependent conformational changes. To test models concerning the mechanism by which TtRp transfers between different sites on the complex, we monitored (1)H, (15)N, and (13)C NMR signals as a function of redox state and molar ratio of added ligand. Our studies of full-length TtRp were carried out in the presence of dodecyl phosphocholine micelles to solvate the membrane anchor of the protein and the hydrophobic tail of the ligand (hydroubiquinone). NMR data indicated that hydroubiquinone binds to TtRp and stabilizes an altered protein conformation. We utilized a truncated form of the Rieske protein lacking the membrane anchor (trunc-TtRp) to investigate redox-state-dependent conformational changes. Local chemical shift perturbations suggested possible conformational changes at prolyl residues. Detailed investigations showed that all observable prolyl residues of oxidized trunc-TtRp have trans peptide bond configurations but that two of these peptide bonds (Cys151-Pro152 and Gly169-Pro170 located near the iron-sulfur cluster) become cis in the reduced protein. Changes in the chemical shifts of backbone signals provided evidence for redox-state- and ligand-dependent conformational changes localized near the iron-sulfur cluster. These structural changes may alter interactions between the Rieske protein and the cytochrome b and c sites and provide part of driving force for movement of the Rieske protein between these two sites.


PMID: 23480240 [PubMed - as supplied by publisher]



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