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Wildegger, Gudrun ; Bentrop, Detlef ; Ejchart, Andrzej ; Alber, Markus ; Hage, Andrea ; Sterner, Reinhard ; Rösch, Paul:
¹H Nuclear‐Magnetic‐Resonance Investigation of Oxidized Fe₄S₄ Ferredoxin from Thermotoga maritima : Hyperfine‐Shifted Resonances, Sequence‐Specific Assignments and Secondary Structure.
In: European Journal of Biochemistry.
Bd. 229
(1995)
Heft 3
.
- S. 658-668.
ISSN 1432-1033
DOI: https://doi.org/10.1111/j.1432-1033.1995.0658j.x
Abstract
The oxidized Fe4S4 ferredoxin from the hyperthermophilic bacterium Thermotoga maritima has been investigated by one- and two-dimensional NMR in order to characterize its hyperfine-shifted resonances originating from the cysteinyl cluster ligands and to assign its resonances in the diamagnetic shift range. The chemical shift and relaxation time pattern of the hyperfine-shifted signals is very similar to other oxidized Fe4S4 ferredoxins. A tentative sequence-specific assignment of these resonances according to a general pattern of chemical shift of cysteine protons versus sequence position of cluster ligand is presented. Furthermore, sequence-specific assignments for 85% of the amino acid residues that were obtained without any guidance by known X-ray structures of ferredoxins are given. They reveal the formation of at least two elements of secondary structure by the polypeptide chain of T. maritima ferredoxin: an alpha-helix comprising residues C43-D49 and a double-stranded antiparallel beta-sheet consisting of the N- and C-terminal parts of the protein. This folding pattern is very similar to that of the crystallographically characterized ferredoxin from the mesophile Desulfovibrio gigas [Kissinger, C.R., Sieker, L.C., Adman E.T. & Jensen, L.H. (1991) J. Mol. Biol. 219, 693-715] and therefore suggesting different mechanisms of stabilization for T. maritima ferredoxin and the ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus that was recently investigated by NMR [Teng, Q., Zhou, Z.H., Smith, E.T., Busse, S. C., Howard, J.B., Adams M.W.W. & La Mar, G.N. (1994) Biochemistry 33, 6316-6326].