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PMID:23586717

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Citation

Qian, L, Zheng, C and Liu, J (2013) Characterization of Iron-Sulfur Cluster Assembly Protein IscA from Acidithiobacillus ferrooxidans. Biochemistry Mosc. 78:244-51

Abstract

IscA is a key member of the iron-sulfur cluster assembly machinery found in bacteria and eukaryotes, but the mechanism of its function in the biogenesis of iron-sulfur cluster remains elusive. In this paper, we demonstrate that Acidithiobacillus ferrooxidans IscA is a [4Fe-4S] cluster binding protein, and it can bind iron in the presence of DTT with an apparent iron association constant of 4·10(20) M(-1). The iron binding in IscA can be promoted by oxygen through oxidizing ferrous iron to ferric iron. Furthermore, we show that the iron bound form of IscA can be converted to iron-sulfur cluster bound form in the presence of IscS and L-cysteine in vitro. Substitution of the invariant cysteine residues Cys35, Cys99, or Cys101 in IscA abolishes the iron binding activity of the protein; the IscA mutants that fail to bind iron are unable to assemble the iron-sulfur clusters. Further studies indicate that the iron-loaded IscA could act as an iron donor for the assembly of iron-sulfur clusters in the scaffold protein IscU in vitro. Taken together, these findings suggest that A. ferrooxidans IscA is not only an iron-sulfur protein, but also an iron binding protein that can act as an iron donor for biogenesis of iron-sulfur clusters.

Links

PubMed Online version:10.1134/S000629791303005X

Keywords


Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ACIF5:B5ENY3

GO:0005506: iron ion binding

IDA: Inferred from Direct Assay:

F

Figure 2.

complete
CACAO 8419


ACIF5:B5ENY3

GO:0005506: iron ion binding

IDA: Inferred from Direct Assay:

F

Seeded From UniProt

complete


ACIF2:B7J5X1

GO:0005506: iron ion binding

ECO:0000314:

F

Figure 2.

complete
CACAO 8420

ACIF2:B7J5X1

enables

GO:0005506: iron ion binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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