Cell death suppressor Arabidopsis bax inhibitor-1 is associated with calmodulin binding and ion homeostasis

Plant Physiol. 2007 Feb;143(2):650-60. doi: 10.1104/pp.106.090878. Epub 2006 Dec 1.


Cell death suppressor Bax inhibitor-1 (BI-1), an endoplasmic reticulum membrane protein, exists in a wide range of organisms. The split-ubiquitin system, overlay assay, and bimolecular fluorescence complementation analysis demonstrated that Arabidopsis (Arabidopsis thaliana) BI-1 (AtBI-1) interacted with calmodulin in yeast (Saccharomyces cerevisiae) and in plant cells. Furthermore, AtBI-1 failed to rescue yeast mutants lacking Ca2+ ATPase (Pmr1 or Spf1) from Bax-induced cell death. Pmr1 and Spf1, p-type ATPases localized at the inner membrane, are believed to be involved in transmembrane movement of calcium ions in yeast. Thus, the presence of intact Ca2+ ATPases was essential for AtBI-1-mediated cell death suppression in yeast. To investigate the effect of AtBI-1 on calcium homeostasis, we evaluated sensitivity against cyclopiazonic acid (CPA), an inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase in AtBI-1-overexpressing or knock-down transgenic Arabidopsis plants. These plants demonstrated altered CPA or ion stress sensitivity. Furthermore, AtBI-1-overexpressing cells demonstrated an attenuated rise in cytosolic calcium following CPA or H2O2 treatment, suggesting that AtBI-1 affects ion homeostasis in plant cell death regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Calcium / metabolism
  • Calmodulin / metabolism*
  • Cell Death / physiology*
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation, Plant
  • Homeostasis*
  • Hordeum / genetics
  • Hordeum / metabolism
  • Indoles / pharmacology
  • Ions / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Plants, Genetically Modified
  • Protein Binding


  • ATBI-1 protein, Arabidopsis
  • Arabidopsis Proteins
  • Calmodulin
  • Enzyme Inhibitors
  • Indoles
  • Ions
  • MLO protein, Hordeum vulgare
  • Membrane Proteins
  • Plant Proteins
  • Calcium
  • cyclopiazonic acid