PIP2 Interacts Electrostatically with MARCKS-like Protein-1 and ENaC in Renal Epithelial Cells

• Type of Material: Article
• Authors: Qiang Yue, Emory University; Otor Al-Khalili, Emory University; Auriel Moseley, Emory University; Masaaki Yoshigi, University of Utah; Brandi Wynne, Emory University; He-Ping Ma, Emory University; Douglas Eaton, Emory University
• Language: English
• Date: 2022-12-01
• Publisher: MDPI
• Publication Version: Final Published Version
• Copyright Statement: © 2022 by the authors.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3390/biology11121694
• Title of Journal or Parent Work: BIOLOGY-BASEL
• Volume: 11
• Issue: 12
• Grant/Funding Information: Supported by R01 DK-110409 to DCE and K01 DK-115660 and ASN Gottschalk AWARD to B.M.W.
• Keywords: MARCKS-like protein-1; PIP2; ENaC; Life Sciences & Biomedicine; MARCKS-like-1; NA+ CHANNEL; LIPID RAFTS; Science & Technology; 3,4,5-TRISPHOSPHATE; COLLECTING DUCT; C-KINASE SUBSTRATE; Life Sciences & Biomedicine - Other Topics; PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE; MEMBRANE; Biology; PI(4,5)P-2; mpkCCD cells; DIRECT ACTIVATION; SODIUM-CHANNEL ENAC
• Research Categories: Health Sciences, Medicine and Surgery

Abstract

We examined the interaction of a membrane-associated protein, MARCKS-like Protein-1 (MLP-1), and an ion channel, Epithelial Sodium Channel (ENaC), with the anionic lipid, phosphatidylinositol 4, 5-bisphosphate (PIP2). We found that PIP2 strongly activates ENaC in excised, inside-out patches with a half-activating concentration of 21 ± 1.17 µM. We have identified 2 PIP2 binding sites in the N-terminus of ENaC β and γ with a high concentration of basic residues. Normal channel activity requires MLP-1’s strongly positively charged effector domain to electrostatically sequester most of the membrane PIP2 and increase the local concentration of PIP2. Our previous data showed that ENaC covalently binds MLP-1 so PIP2 bound to MLP-1 would be near PIP2 binding sites on the cytosolic N terminal regions of ENaC. We have modified the charge structure of the PIP2 –binding domains of MLP-1 and ENaC and showed that the changes affect membrane localization and ENaC activity in a way consistent with electrostatic theory.