Download MendeleyNir2 crystal structures reveal a phosphatidic acid-sensing mechanism at ER-PM contact sites.
Kim, D., Lee, S., Jun, Y., Lee, C.(2025) Proc Natl Acad Sci U S A 122: e2516849122-e2516849122
- PubMed: 41129229
- DOI: https://doi.org/10.1073/pnas.2516849122
- Primary Citation of Related Structures:
9JTZ, 9JUI, 9JYX, 9JZ1, 9JZP - PubMed Abstract:
Agonist-induced activation of phosphoinositide-specific phospholipase C (PLC) converts phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ] to diacylglycerol (DAG) at the inner leaflet of the plasma membrane (PM). DAG can be enzymatically transformed into phosphatidic acid (PA) and accumulated at the PM. PYK2 N-terminal domain-interacting receptor 2 (Nir2) mediates the formation of ER-PM membrane contact sites (MCSs) by specifically recognizing PA at the PM and directly interacting with ER membrane protein vesicle-associated membrane protein-associated proteins (VAPs). The N-terminal phosphatidylinositol transfer protein domain of Nir2 facilitates PI/PA exchange at ER-PM MCSs to maintain PI and PA levels. Here, we reveal the mechanisms by which Nir2 senses phosphatidic acid (PA) and associates with membranes, based on three crystal structures of its C-terminal Lipin/Ned1/Smp2 (LNS2) domain bound to PA, the diphenylalanine [FF]-containing acidic tract (FFAT) motif complexed with vesicle-associated membrane protein-associated protein B/C (VAPB), and the Asp-Asp-His-Asp (DDHD) domain. The C-terminal LNS2 domain of Nir2 directly interacts with the phosphate in the headgroup of PA via hydrogen bonds involving S1025, T1065, K1103, and K1126. Formation of a salt bridge between E355 in Nir2 and R55 in VAPB is essential for Nir2 FFAT-VAPB interaction. The central DDHD domain of Nir2 forms a twofold symmetric dimer, and this self-association contributes to stable and tight membrane association. These findings reveal how Nir2-mediated ER-PM MCS formation maintains continued PI(4,5)P 2 -dependent PLC signaling.
- Department of Life Sciences, Korea University, Seoul 02841, South Korea.
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