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Nutritional immunity: homology modeling of Nramp metal import

Mathieu F M Cellier1

  • 1INRS-Institut Armand-Frappier, Institut National de la Recherche Scientifique, 531, Bd des prairies, H7V 1B7, Laval, QC, Canada. mathieu.cellier@iaf.inrs.ca

Advances in Experimental Medicine and Biology
|September 28, 2011
PubMed

Insights

Researchers modeled the 3D structure of Natural resistance-associated macrophage proteins (Nramp) using homology to bacterial transporters. This model reveals how these iron and manganese transporters function in macrophages and their evolutionary links.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Background:

  • Natural resistance-associated macrophage proteins (Nramp1 and 2), also known as Slc11a1 and 2, are proton-dependent transporters for divalent metals like iron (Fe2+) and manganese (Mn2+).
  • Their presence in macrophages with differing iron metabolism raises questions about their transport mechanism and function in various cellular states.

Purpose of the Study:

  • To elucidate the 3D structure and transport mechanism of Slc11 (Nramp) carriers.
  • To provide a structural framework for understanding Nramp function in macrophages and their evolutionary relationships.

Main Methods:

  • Utilized detailed phylogeny and remote homology threading.
  • Employed the Escherichia coli Nramp homolog (MntH) as an experimental system for modeling.
  • Developed a low-resolution 3D model of Slc11 carriers.

Main Results:

  • A low-resolution 3D model for Slc11 carriers was successfully developed.
  • The predicted structure aligns with experimental data on transmembrane topology and transporter activity.
  • Slc11 carriers were identified as members of the LeuT superfamily, suggesting a conserved structural motif.

Conclusions:

  • Homology modeling suggests an inverted structural symmetry facilitates proton-driven divalent metal import by Slc11 carriers.
  • The 3D model provides a basis for structure-activity relationship studies in macrophages.
  • This work offers insights into the functional evolution of MntH/Nramp (Slc11) carriers.

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