The Unfolded Protein Response Modulates a Phosphoinositide-Binding Protein through the IRE1-bZIP60 Pathway

• Published in: Plant physiology (Bethesda) Vol. 183; no. 1; pp. 221 - 235
• Main Authors: Yu, Chao-Yuan, Kanehara, Kazue
• Format: Journal Article
• Language: English
• Published: United States 01.05.2020
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Carrier Proteins; Cell Membrane - genetics; Cell Membrane - metabolism; Endoplasmic Reticulum - genetics; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum Stress - genetics; Endoplasmic Reticulum Stress - physiology; Gene Expression Regulation, Plant; Golgi Apparatus - genetics; Golgi Apparatus - metabolism; Phosphatidylinositols - metabolism; Signal Transduction - genetics; Signal Transduction - physiology; Unfolded Protein Response - genetics; Unfolded Protein Response - physiology
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.19.01488

Phosphoinositides function as lipid signals in plant development and stress tolerance by binding with partner proteins. We previously reported that Arabidopsis ( ) phosphoinositide-specific phospholipase C2 functions in the endoplasmic reticulum (ER) stress response. However, the underlying molecular mechanisms of how phosphoinositides act in the ER stress response remain elusive. Here, we report that a phosphoinositide-binding protein, ( ), is involved in the ER stress tolerance. SVB contains a DUF538 domain with unknown function; orthologs are exclusively found in Viridiplantae. We established that SVB is ubiquitously expressed in plant tissues and is localized to the ER, Golgi apparatus, prevacuolar compartment, and plasma membrane. The knockout mutants of showed enhanced tolerance to ER stress, which was genetically complemented by transducing genomic showed time-dependent induction after tunicamycin-induced ER stress, which depended on and but not and in the unfolded protein response (UPR). A protein-lipid overlay assay showed specific binding of SVB to phosphatidylinositol 3,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. SVB is therefore suggested to be the plant-specific phosphoinositide-binding protein whose expression is controlled by the UPR through the IRE1-bZIP60 pathway in Arabidopsis.