1i6e
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SOLUTION STRUCTURE OF THE FUNCTIONAL DOMAIN OF PARACOCCUS DENITRIFICANS CYTOCHROME C552 IN THE OXIDIZED STATE
OverviewOverview
A soluble and fully functional 10.5 kDa fragment of the 18.2 kDa, membrane-bound cytochrome c(552) from Paracoccus denitrificans has been, heterologously expressed and (13)C/(15)N-labeled to study the structural, features of this protein in both redox states. Well-resolved solution, structures of both the reduced and oxidized states have been determined, using high-resolution heteronuclear NMR. The overall protein topology, consists of two long terminal helices and three shorter helices, surrounding the heme moiety. No significant redox-induced structural, differences have been observed. (15)N relaxation rates and heteronuclear, NOE values were determined at 500 and 600 MHz. Several residues located, around the heme moiety display increased backbone mobility in both, oxidation states, while helices I, III, and V as well as the two, concatenated beta-turns between Leu30 and Arg36 apparently form a less, flexible domain within the protein structure. Major redox-state-dependent, differences of the internal backbone mobility on the picosecond-nanosecond, time scale were not evident. Hydrogen exchange experiments demonstrated, that the slow-exchanging amide proton resonances mainly belong to the, helices and beta-turns, corresponding to the regions with high order, parameters in the dynamics data. Despite this correlation, the backbone, amide protons of the oxidized cytochrome c(552) exchange considerably, faster with the solvent compared to the reduced protein. Using both, differential scanning calorimetry as well as temperature-dependent NMR, spectroscopy, a significant difference in the thermostabilities of the two, redox states has been observed, with transition temperatures of 349.9 K, (76.8 degrees C) for reduced and 307.5 K (34.4 degrees C) for oxidized, cytochrome c(552). These results suggest a clearly distinct backbone, stability between the two oxidation states.
About this StructureAbout this Structure
1I6E is a Single protein structure of sequence from Paracoccus denitrificans with HEC as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Solution structure and dynamics of the functional domain of Paracoccus denitrificans cytochrome c(552) in both redox states., Reincke B, Perez C, Pristovsek P, Lucke C, Ludwig C, Lohr F, Rogov VV, Ludwig B, Ruterjans H, Biochemistry. 2001 Oct 16;40(41):12312-20. PMID:11591150 [[Category: isotope enrichment {13c/15n}]]
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