Bacterial ApbC can bind and effectively transfer iron-sulfur clusters.
The metabolism of iron-sulfur ([Fe-S]) clusters requires a complex set of machinery that is still being defined. Mutants of Salmonella enterica lacking apbC have nutritional and biochemical properties indicative of defects in [Fe-S] cluster metabolism. ApbC is a 40.8 kDa homodimeric ATPase and as purified contains little iron and no acid-labile sulfide. An [Fe-S] cluster was reconstituted on ApbC, generating a protein that bound 2 mol of Fe and 2 mol of S (2-) per ApbC monomer and had a UV-visible absorption spectrum similar to known [4Fe-4S] cluster proteins. Holo-ApbC could rapidly and effectively activate Saccharomyces cerevisiae apo-isopropylmalate isolomerase (Leu1) in vitro, a process known to require the transfer of a [4Fe-4S] cluster. Maximum activation was achieved with 2 mol of ApbC per 1 mol of apo-Leu1. This article describes the first biochemical activity of ApbC in the context of [Fe-S] cluster metabolism. The data herein support a model in which ApbC coordinates an [4Fe-4S] cluster across its dimer interface and can transfer this cluster to an apoprotein acting as an [Fe-S] cluster scaffold protein, a function recently deduced for its eukaryotic homologues.
Boyd
Jeffrey M
JM
Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, USA.
Pierik
Antonio J
AJ
Netz
Daili J A
DJ
Lill
Roland
R
Downs
Diana M
DM
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007535:Isomerases / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism*
C470751:ApbC protein, Salmonella typhimurium; D001426:Bacterial Proteins; C520224:Cfd1 protein, S cerevisiae; C102265:NBP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013455:Sulfur; D007501:Iron; D000251:Adenosine Triphosphatases; D019204:GTP-Binding Proteins; C032241:isopropylmalate isomerase; D007535:Isomerases