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The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis

Author:
  • Stephan Wagner
  • Smrutisanjita Behera
  • Sara De Bortoli
  • David C Logan
  • Philippe Fuchs
  • Luca Carraretto
  • Enrico Teardo
  • Laura Cendron
  • Thomas Nietzel
  • Magdalena Füßl
  • Fabrizio G Doccula
  • Lorella Navazio
  • Mark D Fricker
  • Olivier Van Aken
  • Iris Finkemeier
  • Andreas J Meyer
  • Ildikò Szabò
  • Alex Costa
  • Markus Schwarzländer
Publishing year: 2015-11
Language: English
Pages: 212-3190
Publication/Series: Plant Cell
Volume: 27
Issue: 11
Document type: Journal article
Publisher: American Society of Plant Biologists

Abstract english

Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca(2+) signaling may play a central role in this process. Free Ca(2+) dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca(2+) dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca(2+) uniporter machinery in mammals. MICU binds Ca(2+) and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca(2+) sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca(2+) in the matrix. Furthermore, Ca(2+) elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca(2+) signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca(2+) uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca(2+) uptake by moderating influx, thereby shaping Ca(2+) signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca(2+) signaling in plants.

Keywords

  • Biochemistry and Molecular Biology
  • Arabidopsis
  • Arabidopsis Proteins
  • Calcium
  • Calcium Signaling
  • Calcium-Binding Proteins
  • Cell Respiration
  • Cytosol
  • DNA, Bacterial
  • EF Hand Motifs
  • Mitochondria
  • Mutagenesis, Insertional
  • Phylogeny
  • Plant Roots
  • Protein Binding
  • Protein Transport
  • Seedlings
  • Sequence Homology, Amino Acid
  • Subcellular Fractions
  • Journal Article
  • Research Support, Non-U.S. Gov't

Other

Published
  • ISSN: 1040-4651
Olivier van Aken
E-mail: olivier [dot] van_aken [at] biol [dot] lu [dot] se

Senior lecturer

Molecular Cell Biology

+46 46 222 94 13

B-A330

4

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Plant Biology

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