The structure of ferricytochrome c' from Rhodospirillum molischianum has been crystallographically refined to 1.67 A resolution using a combination of reciprocal space and restrained least-squares refinement methods. The final crystallographic R-factor for 30,533 reflections measured with I greater than sigma (I) between infinity and 1 ...
The structure of ferricytochrome c' from Rhodospirillum molischianum has been crystallographically refined to 1.67 A resolution using a combination of reciprocal space and restrained least-squares refinement methods. The final crystallographic R-factor for 30,533 reflections measured with I greater than sigma (I) between infinity and 1.67 A is 0.188. The final model incorporates 1944 unique protein atoms (of a total of 1972) together with 194 bound solvent molecules. The structure has been analysed with respect to its detailed conformational properties, secondary structural features, temperature factor behavior, bound solvent sites, and heme geometry. The asymmetric unit of the cytochrome c' crystal contains a dimer composed of chemically identical 128-residue polypeptide chains. Although the refined structure shows the monomers to be very similar, examination of the differences that do occur allows an evaluation of how different lattice contacts affect protein conformation and solvent binding. In particular, comparison of solvent binding sites in the two subunits allows identification of a common set that are not altered by lattice interactions. The preservation of these solvent interactions in different lattice environments suggests that they play a structural role in protein stabilization in solution. The refined structure additionally reveals some new features that relate to the ligand binding properties and unusual mixed-spin state character of cytochrome c'. Finally, comparison of the heme binding geometry in cytochrome c' and other structurally unrelated c-type cytochromes shows that two alternative, but sterically favorable, conformational variants occur among the seven examples examined.
Related Citations:
Lattice Mobility and Anomalous Temperature Factor Behaviour in Cytochrome C(Prime) Finzel, B.C., Salemme, F.R. (1985) Nature 315: 686
Crystallographic Structure of Rhodospirillum Molischianum Ferricytochrome C(Prime) at 2.5 Angstroms Resolution Weber, P.C., Howard, A., Xuong, N.H., Salemme, F.R. (1981) J Mol Biol 153: 399
Correlations between Structural and Spectroscopic Properties of the High-Spin Heme Protein Cytochrome C(Prime) Weber, P.C. (1982) Biochemistry 21: 5116
On the Evolutionary Relationship of the 4-Alpha-Helical Heme Proteins. The Comparison of Cytochrome B562 and Cytochrome C(Prime) Weber, P.C., Salemme, F.R., Mathews, F.S., Bethge, P.H. (1981) J Biol Chem 256: 7702
Structural and Functional Diversity in 4-Alpha-Helical Proteins Weber, P.C., Salemme, F.R. (1980) Nature 287: 82
Structure of Cytochrome C(Prime). A Dimeric, High-Spin Haem Protein Weber, P.C., Bartsch, R.G., Cusanovich, M.A., Hamlin, R.C., Howard, A., Jordan, S.R., Kamen, M.D., Meyer, T.E., Weatherford, D.W., Xuong, N.H., Salemme, F.R. (1980) Nature 286: 302
Preliminary Crystallographic Data for Cytochromes C(Prime) of Rhodopseudomonas Capsulata and Rhodospirillum Molischianum Weber, P., Salemme, F.R. (1977) J Mol Biol 117: 815
Organizational Affiliation:
The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand.
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