The chloroplast NifS-like protein of Arabidopsis thaliana is required for iron-sulfur cluster formation in ferredoxin

Planta. 2005 Feb;220(4):602-8. doi: 10.1007/s00425-004-1388-1. Epub 2004 Oct 8.

Abstract

Plastids are known to be able to synthesize their own iron-sulfur clusters, but the biochemical machinery responsible for this process is not known. In this study it is investigated whether CpNifS, the chloroplastic NifS-like cysteine desulfurase of Arabidopsis thaliana (L.) Heynh. is responsible for the release of sulfur from cysteine for the biogenesis of iron-sulfur (Fe-S) clusters in chloroplasts. Using an in vitro reconstitution assay it was found that purified CpNifS was sufficient for Fe-S cluster formation in ferredoxin in the presence of cysteine and a ferrous iron salt. Antibody-depletion experiments using stromal extract showed that CpNifS is also essential for the Fe-S cluster formation activity of chloroplast stroma. The activity of CpNifS in the stroma was 50- to 80-fold higher than that of purified CpNifS on a per-protein basis, indicating that other stromal factors cooperate in Fe-S cluster formation. When stromal extract was separated on a gel-filtration column, most of the CpNifS eluted as a dimer of 86 kDa, but a minor fraction of the stromal CpNifS eluted at a molecular weight of approx. 600 kDa, suggesting the presence of a multi-protein complex. The possible nature of the interacting proteins is discussed.

Publication types

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

MeSH terms

  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Chloroplasts / metabolism*
  • Chromatography, Gel
  • Ferredoxins / metabolism*
  • Iron-Sulfur Proteins / metabolism*
  • Kinetics

Substances

  • Arabidopsis Proteins
  • At1g08490 protein, Arabidopsis
  • Ferredoxins
  • Iron-Sulfur Proteins