The BEACH Domain Protein SPIRRIG Is Essential for Arabidopsis Salt Stress Tolerance and Functions as a Regulator of Transcript Stabilization and Localization

PLoS Biol. 2015 Jul 2;13(7):e1002188. doi: 10.1371/journal.pbio.1002188. eCollection 2015 Jul.


Members of the highly conserved class of BEACH domain containing proteins (BDCPs) have been established as broad facilitators of protein-protein interactions and membrane dynamics in the context of human diseases like albinism, bleeding diathesis, impaired cellular immunity, cancer predisposition, and neurological dysfunctions. Also, the Arabidopsis thaliana BDCP SPIRRIG (SPI) is important for membrane integrity, as spi mutants exhibit split vacuoles. In this work, we report a novel molecular function of the BDCP SPI in ribonucleoprotein particle formation. We show that SPI interacts with the P-body core component DECAPPING PROTEIN 1 (DCP1), associates to mRNA processing bodies (P-bodies), and regulates their assembly upon salt stress. The finding that spi mutants exhibit salt hypersensitivity suggests that the local function of SPI at P-bodies is of biological relevance. Transcriptome-wide analysis revealed qualitative differences in the salt stress-regulated transcriptional response of Col-0 and spi. We show that SPI regulates the salt stress-dependent post-transcriptional stabilization, cytoplasmic agglomeration, and localization to P-bodies of a subset of salt stress-regulated mRNAs. Finally, we show that the PH-BEACH domains of SPI and its human homolog FAN (Factor Associated with Neutral sphingomyelinase activation) interact with DCP1 isoforms from plants, mammals, and yeast, suggesting the evolutionary conservation of an association of BDCPs and P-bodies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / physiology*
  • Arabidopsis Proteins / metabolism*
  • Endoribonucleases / metabolism
  • Evolution, Molecular
  • Gene Expression Regulation, Plant*
  • Genetic Pleiotropy
  • RNA, Messenger / metabolism
  • Salt Tolerance*


  • Arabidopsis Proteins
  • RNA, Messenger
  • SPIRRIG protein, Arabidopsis
  • Endoribonucleases
  • Dcp1 protein, Arabidopsis

Grants and funding

This work was supported by the Deutsche Forschungsgemeinschaft, Priority Program Sonderforschungsprogram 635 to MH. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.