Open Access1 H‐NMR studies of high‐potential iron‐sulfur protein from the purple phototrophic bacterium, Rhodospirillum tenue
Author(s) -
KRISHNAMOORTHI Ramaswamy,
CUSANOVICH Michael A.,
MEYER Terrence E.,
PRZYSIECKI Craig T.
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb14696.x
Subject(s) - rhodospirillales , rhodospirillaceae , iron–sulfur cluster , hyperfine structure , sulfur , ferredoxin , crystallography , biology , purple bacteria , titration , stereochemistry , chemistry , photosynthesis , botany , biochemistry , enzyme , physics , inorganic chemistry , photosynthetic reaction centre , organic chemistry , quantum mechanics
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 1 H‐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.