Salmonella enterica Requires ApbC Function for Growth on Tricarballylate: Evidence of Functional Redundancy between ApbC and IscU

Department of Bacteriology, 1550 Linden Drive, University of Wisconsin, Madison, WI 53706, USA.
Journal of bacteriology (Impact Factor: 2.81). 08/2008; 190(13):4596-602. DOI: 10.1128/JB.00262-08
Source: PubMed

ABSTRACT Mutants of Salmonella enterica lacking apbC have nutritional and biochemical properties indicative of defects in [Fe-S] cluster metabolism. Here we show that apbC is required for S. enterica to use tricarballylate as a carbon and energy source. Tricarballylate catabolism requires three gene products, TcuA, TcuB, and TcuC. Of relevance to this work is the TcuB protein, which has two [4Fe-4S] clusters required for function, making it a logical target for the apbC effect. TcuB activity was 100-fold lower in an apbC mutant than in the isogenic apbC(+) strain. Genetic data show that derepression of the iscRSUA-hscAB-fdx-orf3 operon or overexpression of iscU from a plasmid compensates for the lack of ApbC during growth on tricarballylate. The studies described herein provide evidence that the scaffold protein IscU has a functional overlap with ApbC and that ApbC function is involved in the synthesis of active TcuB.

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    • "Mrp is a member of the ATPase ParA-like family, which shares sequence similarity with eukaryotic proteins involved in Fe/S cluster biogenesis, such as Nbp35 and Cfd1 [100] [101] [102]. In Salmonella enterica, ApbC was proposed to be a scaffold as an increased apbC gene dosage could suppress iscU mutations [99]. However, the archaeal ApbC/Nbp35 homolog was described as a carrier rather than a scaffold [100]. "
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