Evidence for polynuclear iron(III) clusters in the root nodule bacterium, Rhizobium leguminosarum bv. viciae WSM710.

Citation
Tg. St Pierre et al., Evidence for polynuclear iron(III) clusters in the root nodule bacterium, Rhizobium leguminosarum bv. viciae WSM710., BIOMETALS, 12(1), 1999, pp. 73-76
Citations number
27
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOMETALS
ISSN journal
09660844 → ACNP
Volume
12
Issue
1
Year of publication
1999
Pages
73 - 76
Database
ISI
SICI code
0966-0844(199903)12:1<73:EFPICI>2.0.ZU;2-Y
Abstract
Cells of the root nodule bacterium Rhizobium leguminosarum bv. viciae WSM71 0 were cultured in a medium containing 20 mu M Fe-57. Mossbauer spectra of the cells at 5.5 and 3.7 K indicated that the major form of iron present in the cells was in the form of polynuclear iron(III) clusters. At 5.5 K the spectral component associated with these clusters was in the form of a supe rposition of a broad feature (large magnetic hyperfine field distribution) and a doublet. On lowering the temperature of the cells to 3.7 K, the spect ral component was transformed into resolved magnetic hyperfine field splitt ing which yielded a magnetic hyperfine field of 42.4 T when fitted with bro ad Lorentzian peaks. These spectral characteristics are typical of the hydr ated iron(III) phosphate cores of several bacterioferritins. A small fracti on (11%) of the Mossbauer spectral area of the cells was in the form of a d oublet which yielded parameters (delta = 1.35 mm/s; Delta E-Q = 3.15 mm/s) indicative of iron(II). The parameters are very similar to those of a spect ral component previously observed in several other microbes (R. Bohnke and B.F. Matzanke (1995) BioMetals 8, 223-230) and which has been associated wi th a 2.2 kDa oligomeric iron(II) carbohydrate phosphate.