The intrinsically disordered protein NUPR1 binds to phospholipids

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Nuclear protein 1 (NUPR1) is an intrinsically disordered protein (IDP) known to interact with proteins and nucleic acids.
• NUPR1 plays a role in cellular responses to stress.
• The conformational flexibility of NUPR1 suggests potential interactions with other biomolecules, including lipids.

Purpose of the Study:

• To investigate whether NUPR1 interacts with lipids.
• To characterize the binding of NUPR1 to specific phospholipids.
• To explore the potential biological implications of NUPR1-lipid interactions.

Main Methods:

• Proximity ligation assay (PLA) in MiaPaCa-2 cells to verify in cellulo binding.
• In vitro binding assays using nuclear magnetic resonance (NMR) and biolayer interferometry (BLI).
• In silico modeling to analyze NUPR1-lipid interactions on membrane surfaces.

Main Results:

• Binding of NUPR1 to phosphatidylserine (PS) and phosphatidylinositol biphosphate (PIP2) was confirmed in cellulo.
• In vitro experiments validated NUPR1 binding to PS and a PS/phosphatidylcholine (PC) mixture.
• In silico analysis revealed mostly non-specific membrane surface association with preferred binding sites near Ala33 and Thr68.

Conclusions:

• NUPR1 unambiguously binds to lipids, including PS and PIP2.
• These findings suggest NUPR1 may contribute to the stability of membrane organelles.
• NUPR1-lipid interactions could play a role in modulating cellular signaling pathways.