A PCBP1-BolA2 chaperone complex delivers iron for cytosolic [2Fe-2S] cluster assembly

Nat Chem Biol. 2019 Sep;15(9):872-881. doi: 10.1038/s41589-019-0330-6. Epub 2019 Aug 12.

Abstract

Hundreds of cellular proteins require iron cofactors for activity, and cells express systems for their assembly and distribution. Molecular details of the cytosolic iron pool used for iron cofactors are lacking, but iron chaperones of the poly(rC)-binding protein (PCBP) family play a key role in ferrous ion distribution. Here we show that, in cells and in vitro, PCBP1 coordinates iron via conserved cysteine and glutamate residues and a molecule of noncovalently bound glutathione (GSH). Proteomics analysis of PCBP1-interacting proteins identified BolA2, which functions, in complex with Glrx3, as a cytosolic [2Fe-2S] cluster chaperone. The Fe-GSH-bound form of PCBP1 complexes with cytosolic BolA2 via a bridging Fe ligand. Biochemical analysis of PCBP1 and BolA2, in cells and in vitro, indicates that PCBP1-Fe-GSH-BolA2 serves as an intermediate complex required for the assembly of [2Fe-2S] clusters on BolA2-Glrx3, thereby linking the ferrous iron and Fe-S distribution systems in cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Carrier Proteins
  • Cytosol / metabolism
  • DNA-Binding Proteins
  • Doxycycline / pharmacology
  • Ferric Compounds / pharmacology
  • Gene Expression Regulation / drug effects
  • HEK293 Cells
  • Heterogeneous-Nuclear Ribonucleoproteins / genetics
  • Heterogeneous-Nuclear Ribonucleoproteins / metabolism*
  • Humans
  • Iron / metabolism*
  • Iron-Sulfur Proteins / metabolism*
  • Proteins / genetics
  • Proteins / metabolism*
  • Quaternary Ammonium Compounds / pharmacology
  • RNA-Binding Proteins

Substances

  • Anti-Bacterial Agents
  • BOLA2 protein, human
  • Carrier Proteins
  • DNA-Binding Proteins
  • Ferric Compounds
  • GLRX3 protein, human
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Iron-Sulfur Proteins
  • PCBP1 protein, human
  • Proteins
  • Quaternary Ammonium Compounds
  • RNA-Binding Proteins
  • Iron
  • Doxycycline
  • ferric ammonium citrate