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Determination of the [Fe 4 S 4 ]Cys 4 cluster geometry of Desulfovibrio africanus ferredoxin I by 1 H NMR spectroscopy
Author(s) -
Davy Sharon L.,
Osborne Michael J.,
Breton Jacques,
Moore Geoffrey R.,
Thomson Andrew J.,
Bertini Ivano,
Luchinat Claudio
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00317-3
Subject(s) - ferredoxin , dihedral angle , chemistry , crystallography , desulfovibrio , nuclear magnetic resonance spectroscopy , cluster (spacecraft) , nmr spectra database , stereochemistry , spectral line , physics , hydrogen bond , molecule , organic chemistry , astronomy , computer science , sulfate , programming language , enzyme
1D and 2D 1 H NMR studies of the Fe 4 S 4 , cluster containing ferredoxin I from Desulfovibrio africanus have been carried out with the aim of determining the geometry of the cluster linkages with the 4 Cys side chains that bind the cluster. This required the Cys βCH resonances of the oxidised protein to be sequence‐specifically and stereo‐specifically assigned, and this was accomplished by a combination of TOCSY and NOE measurements, allied to model building based on X‐ray structures of related ferredoxins. An analysis of the estimated hyperfine shifts of the Cys βCH resonances with a Karplus‐type equation relating the shifts to iron‐sulfur‐β carbon‐/3 proton dihedral angles, taken together with the relative relaxation rates of the two βCH 2 resonances, estimated from their linewidths, then allowed the ironsulfur‐/3‐carbon‐α‐carbon dihedral angles to be determined. A novel representation of the NMR data is presented which shows that the cluster dihedral angles are uniquely determined by the NMR data. The analysis reveals that the dihedral angles for D. africanus ferredoxin I are similar to the corresponding angles of other ferrredoxins even though there are differences in their 1 H NMR spectra. The sequence‐specific and stereospecific assignments have been extended by analogy to the related Fe 4 S 4 ‐containing D. gigas ferredoxin I, and the stereospecific assignments to the Fe 4 S 4 ‐containing Thermococcus litoralis ferredoxin.