title: 1H nuclear-magnetic-resonance investigation of oxidized Fe4S4 ferredoxin from Thermotoga maritima. Hyperfine-shifted resonances, sequence-specific assignments and secondary structure.
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].
authors.affiliation: Lehrstuhl für Struktur und Chemie der Biopolymere, Universität Bayreuth, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Wildegger
authors.forename: D
authors.initials: D
authors.lastname: Bentrop
authors.forename: A
authors.initials: A
authors.lastname: Ejchart
authors.forename: M
authors.initials: M
authors.lastname: Alber
authors.forename: A
authors.initials: A
authors.lastname: Hage
authors.forename: R
authors.initials: R
authors.lastname: Sterner
authors.forename: P
authors.initials: P
authors.lastname: Rösch
mesh_terms: D000595:Amino Acid Sequence; D003545:Cysteine / Q000737:chemistry; D005288:Ferredoxins / Q000737:chemistry*; D006089:Gram-Negative Anaerobic Bacteria / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment
chemical_list: D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D003545:Cysteine