Co-immunoprecipitation-based identification of putative BAX INHIBITOR-1-interacting proteins involved in cell death regulation and plant-powdery mildew interactions

Mol Plant Pathol. 2013 Oct;14(8):791-802. doi: 10.1111/mpp.12050. Epub 2013 Jun 19.


The endoplasmic reticulum (ER)-resident BAX INHIBITOR-1 (BI-1) protein is one of a few cell death suppressors known to be conserved in animals and plants. The function of BI-1 proteins in response to various biotic and abiotic stress factors is well established. However, little is known about the underlying mechanisms. We conducted co-immunoprecipitation (co-IP) experiments to identify Arabidopsis thaliana BI-1-interacting proteins to obtain a potentially better understanding of how BI-1 functions during plant-pathogen interactions and as a suppressor of cell death. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) identified 95 proteins co-immunoprecipitated with green fluorescing protein (GFP)-tagged BI-1. Five selected candidate proteins, a RIBOPHORIN II (RPN2) family protein, VACUOLAR ATP SYNTHASE SUBUNIT A (VHA-A), cytochrome P450 83A1 (CYP83A1), H(+) -ATPASE 1 (AHA1) and PROHIBITIN 2 (PHB2), were further investigated with regard to their role in BI-1-associated processes. To this end, we analysed a set of Arabidopsis mutants in the interaction with the adapted powdery mildew fungus Erysiphe cruciferarum and on cell death-inducing treatments. Two independent rpn2 knock-down mutants tended to better support powdery mildew, and a phb2 mutant showed altered responses to cell death-inducing Alternaria alternata f.sp. lycopersici (AAL) toxin treatment. Two independent cyp83a1 mutants showed a strong powdery mildew resistance phenotype and enhanced sensitivity to AAL toxin. Moreover, co-localization studies and fluorescence resonance energy transfer (FRET) experiments suggested a direct interaction of BI-1 with CYP83A1 at the ER.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / cytology*
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology*
  • Arabidopsis Proteins / metabolism*
  • Ascomycota / physiology*
  • Cell Death
  • Cytochrome P-450 Enzyme System / metabolism
  • Endoplasmic Reticulum / metabolism
  • Fluorescent Dyes / metabolism
  • Green Fluorescent Proteins / metabolism
  • Host-Pathogen Interactions*
  • Immunoprecipitation*
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein Binding
  • Recombinant Fusion Proteins / metabolism
  • Staining and Labeling


  • ATBI-1 protein, Arabidopsis
  • Arabidopsis Proteins
  • Fluorescent Dyes
  • Membrane Proteins
  • Peptides
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Cytochrome P-450 Enzyme System
  • CYP83A1 protein, Arabidopsis