Spectroscopic investigation of selective cluster conversion of archaeal zinc-containing ferredoxin from Sulfolobus sp. strain 7

J Biol Chem. 2000 Aug 18;275(33):25391-401. doi: 10.1074/jbc.M909243199.


Archaeal zinc-containing ferredoxin from Sulfolobus sp. strain 7 contains one [3Fe-4S] cluster (cluster I), one [4Fe-4S] cluster (cluster II), and one isolated zinc center. Oxidative degradation of this ferredoxin led to the formation of a stable intermediate with 1 zinc and approximately 6 iron atoms. The metal centers of this intermediate were analyzed by electron paramagnetic resonance (EPR), low temperature resonance Raman, x-ray absorption, and (1)H NMR spectroscopies. The spectroscopic data suggest that (i) cluster II was selectively converted to a cubane [3Fe-4S](1+) cluster in the intermediate, without forming a stable radical species, and that (ii) the local metric environments of cluster I and the isolated zinc site did not change significantly in the intermediate. It is concluded that the initial step of oxidative degradation of the archaeal zinc-containing ferredoxin is selective conversion of cluster II, generating a novel intermediate containing two [3Fe-4S] clusters and an isolated zinc center. At this stage, significant structural rearrangement of the protein does not occur. We propose a new scheme for oxidative degradation of dicluster ferredoxins in which each cluster converts in a stepwise manner, prior to apoprotein formation, and discuss its structural and evolutionary implications.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chromatography, Agarose
  • Crystallography, X-Ray
  • Electron Spin Resonance Spectroscopy
  • Ferredoxins / chemistry*
  • Ferredoxins / metabolism*
  • Iron / chemistry
  • Magnetic Resonance Spectroscopy
  • Microwaves
  • Models, Molecular
  • Oxygen / metabolism
  • Spectrometry, X-Ray Emission
  • Spectrum Analysis, Raman
  • Sulfolobus / chemistry*
  • Zinc / chemistry*


  • Ferredoxins
  • Iron
  • Zinc
  • Oxygen