Proteomic analysis and molecular modelling characterize the iron-regulatory protein haemojuvelin/repulsive guidance molecule c

Mahta Nili, Larry David, Johannes Elferich, Ujwal Shinde, Peter Rotwein

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

HJV (haemojuvelin) plays a key role in iron metabolism in mammals by regulating expression of the liver-derived hormone hepcidin, which controls systemic iron uptake and release. Mutations in HJV cause juvenile haemochromatosis, a rapidly progressing iron overload disorder in humans. HJV, also known as RGMc (repulsive guidance molecule c), is a member of the three-protein RGM family. RGMs are GPI (glycosylphosphatidylinositol)-linked glycoproteins that share ~50% amino acid identity and several structural motifs, including the presence of 14 cysteine residues in analogous locations. Unlike RGMa and RGMb, HJV/RGMc is composed of both single-chain and two-chain isoforms. To date there is no structural information for any member of the RGM family. In the present study we have mapped the disulfide bonds in mouse HJV/RGMc using a proteomics strategy combining sequential MS steps composed of ETD (electron transfer dissociation) and CID (collision-induced dissociation), in which ETD induces cleavage of disulfide linkages, and CID establishes disulfide bond assignments between liberated peptides. The results of the present study identified an HJV/RGMc molecular species containing four disulfide linkages. We predict using ab initio modelling that this molecule is a single-chain HJV/RGMc isoform. Our observations outline a general approach using tandemMS and ab initio molecular modelling to define unknown structural features in proteins.

Original languageEnglish (US)
Pages (from-to)87-95
Number of pages9
JournalBiochemical Journal
Volume452
Issue number1
DOIs
StatePublished - May 15 2013

Keywords

  • Disulfide bond
  • Haemojuvelin
  • Iron metabolism
  • Mass spectrometry
  • Molecular modelling
  • Protein structure
  • Repulsive guidance molecule

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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