The ShuS protein of Shigella dysenteriae is a heme-sequestering protein that also binds DNA.
The ability of Shigella dysenteriae to utilize heme as an iron source is dependent on the iron-regulated expression of a number of genes including the outermembrane receptor ShuA and the cytoplasmic protein ShuS. The ShuS protein has no sequence homology with any proteins of known function and its role in heme acquisition has not been determined. In this paper we describe the purification and characterization of ShuS. The soluble oligomeric protein (650 kDa) is composed of a single type of subunit with a molecular mass of 37 kDa and binds one heme per monomer (Kd = 13 microM). In addition, the ShuS protein was shown to nonspecifically bind double-stranded DNA. It appears, therefore, that ShuS may function as both a heme storage protein, during periods of active heme transport, and as a DNA binding protein to protect the DNA from any ensuing heme mediated oxidative damage.
Wilks
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Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore 21201-1180, USA. awilks@rx.umaryland.edu
D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D001693:Biological Transport, Active; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D006418:Heme / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012762:Shigella dysenteriae / Q000378:metabolism* / Q000472:pathogenicity; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D006418:Heme; D007501:Iron