Journal of Bioenergetics and Biomembranes

, Volume 26, Issue 1, pp 67–88

Structure-function studies of [2Fe-2S] ferredoxins

  • Hazel M. Holden
  • Bruce L. Jacobson
  • John K. Hurley
  • Gordon Tollin
  • Byung-Ha Oh
  • Lars Skjeldal
  • Young Kee Chae
  • Hong Cheng
  • Bin Xia
  • John L. Markley
Article

DOI: 10.1007/BF00763220

Cite this article as:
Holden, H.M., Jacobson, B.L., Hurley, J.K. et al. J Bioenerg Biomembr (1994) 26: 67. doi:10.1007/BF00763220

Abstract

The ability to overexpress [2Fe-2S] ferredoxins inEscherichia coli has opened up exciting research opportunities. High-resolution x-ray structures have been determined for the wild-type ferredoxins produced by the vegetative and heterocyst forms ofAnabaena strain 7120 (in their oxidized states), and these have been compared to structural information derived from multidimensional, multinuclear NMR spectroscopy. The electron delocalization in these proteins in their oxidized and reduced states has been studied by1H,2H,13C, and15N NMR spectroscopy. Site-directed mutagenesis has been used to prepare variants of these ferredoxins. Mutants (over 50) of the vegetative ferredoxin have been designed to explore questions about cluster assembly and stabilization and to determine which residues are important for recognition and electron transfer to the redox partnerAnabaena ferredoxin reductase. The results have shown that serine can replace cysteine at each of the four cluster attachment sites and still support cluster assembly. Electron transfer has been demonstrated with three of the four mutants. Although these mutants are less stable than the wild-type ferredoxin, it has been possible to determine the x-ray structure of one (C49S) and to characterize all four by EPR and NMR. Mutagenesis has identified residues 65 and 94 of the vegetative ferredoxin as crucial to interaction with the reductase. Three-dimensional models have been obtained by x-ray diffraction analysis for several additional mutants: T48S, A50V, E94K (four orders of magnitude less active than wild type in functional assays), and A43S/A45S/T48S/A50N (quadruple mutant).

Key words

[2Fe-2S] ferredoxinselectron transportx-ray crystallographynuclear magnetic resonance spectroscopyfast reaction kineticsmutagenesisiron-sulfur cluster assemblyheterologous expressionstable-isotope labelingAnabaena

Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • Hazel M. Holden
    • 1
    • 4
  • Bruce L. Jacobson
    • 1
  • John K. Hurley
    • 2
  • Gordon Tollin
    • 2
  • Byung-Ha Oh
    • 3
  • Lars Skjeldal
    • 3
  • Young Kee Chae
    • 3
    • 4
  • Hong Cheng
    • 3
  • Bin Xia
    • 3
    • 4
  • John L. Markley
    • 3
    • 4
  1. 1.Institute for Enzyme ResearchUniversity of Wisconsin-MadisonMadison
  2. 2.Department of BiochemistryUniversity of ArizonaTucson
  3. 3.Department of BiochemistryUniversity of Wisconsin-MadisonMadison
  4. 4.Graduate Program in BiophysicsUniversity of Wisconsin-MadisonMadison
  5. 5.SmithKline BeechamKing of Prussia
  6. 6.Department of Biochemical SciencesAgricultural University of Norway, IBFNorway