title: 1H-NMR studies of high-potential iron-sulfur protein from the purple phototrophic bacterium, Rhodospirillum tenue.
abstract: The high-potential iron-sulfur protein (HiPIP) from Rhodospirillum tenue (strain 3761) shows only a weak (20-25%) sequence similarity to HiPIPs from Chromatium vinosum, Ectothiorhodospira halophila and Ectothiorhodospira vacuolata, including the strict conservation of only two of the twelve residues assumed to be in the 4Fe-4S cluster packing region [Tedro, S. M., Meyer, T. E. and Kamen, M. D. (1979) J. Biol. Chem. 254, 1495-1500]. In spite of these differences, the general range and distribution of hyperfine-shifted 1H-NMR peaks of oxidized and reduced R. tenue HiPIP resemble those of E. halophila HiPIP I [Krishnamoorthi, R., Markley, J. L., Cusanovich, M. A., Pryzycieki, C. T. and Meyer, T. E. (1986) Biochemistry 25, 60-67]. Temperature- and pH-dependence and longitudinal relaxation behavior were determined for hyperfine-shifted peaks of the oxidized protein. Tentative assignments of peaks to ligands and aromatic residues suggest the presence of common apoprotein-active-site interactions in these proteins. Differences occur in the pattern of paramagnetically shifted peaks attributed to hydrogens bonded to the 4Fe-4S cluster. Hyperfine-shifted peaks of R. tenue HiPIP are not perturbed by pH changes in the range 5-9. In contrast, those of the C. vinosum protein exhibit a pH-dependence of chemical shifts that has been attributed to the titration of His42 [Nettesheim, D. G., Meyer, T. E., Feinberg, B. A. and Otvos, J. D. (1983) J. Biol. Chem. 258, 8235-8239]. Since R. tenue HiPIP contains no histidine, the present observation confirms the above hypothesis.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison.
authors.forename: R
authors.initials: R
authors.lastname: Krishnamoorthi
authors.forename: M A
authors.initials: MA
authors.lastname: Cusanovich
authors.forename: T E
authors.initials: TE
authors.lastname: Meyer
authors.forename: C T
authors.initials: CT
authors.lastname: Przysiecki
mesh_terms: D006859:Hydrogen; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008667:Metalloproteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D012246:Rhodospirillum / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D006859:Hydrogen