Valine 77 of heterocystous ferredoxin FdxH2 in Anabaena variabilis strain ATCC 29413 is critical for its oxygen sensitivity

Brij B. Singh, I. Curdt, D. Shomburg, P. S. Bisen, H. Bhöme

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Ferredoxins are small iron sulfur proteins necessary for electron donation. FdxH1 and FdxH2 are associated with two different nif gene clusters where they transfer electrons for the reduction of nitrogenase complex. FdxH1 was observed to be stable towards oxygen, whereas, FdxH2 was relatively unstable. We had identified the amino acid involved in oxygen sensitivity of ferredoxin protein using protein modeling. The exchange of valine to leucine at position 77 was critical for ferredoxin proteins in relation to its oxygen sensitivity. This exchange leads to a longer side chain, which inhibits the accessibility of oxygen to the iron sulfur cluster. Site directed mutagenesis and in vitro experiments confirms that valine indeed is involved in the oxygen sensitivity. The exchange of leucine to valine in FdxH1 makes it oxygen unstable. Thus, from the above results we can conclude that the position of leucine at position 77 is critical for oxygen sensitivity of ferredoxin and protein modeling can be used to identify specific amino acids in other oxygen-sensitive proteins.

Original languageEnglish (US)
Pages (from-to)137-142
Number of pages6
JournalMolecular and Cellular Biochemistry
Volume217
Issue number1-2
DOIs
StatePublished - Mar 13 2001
Externally publishedYes

Keywords

  • Ferredoxin
  • Nitrogen fixation
  • Oxygen sensitivity
  • Protein modeling

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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