@article{a73d0be010644ece954df89fd04c3d95,
title = "Phosphatidic acid induces conformational changes in Sec18 protomers that prevent SNARE priming",
abstract = "Eukaryotic cell homeostasis requires transfer of cellular components among organelles and relies on membrane fusion catalyzed by SNARE proteins. Inactive SNARE bundles are reactivated by hexameric N-ethylmaleimide-sensitive factor, vesicle-fusing ATPase (Sec18/NSF)-driven disassembly that enables a new round of membrane fusion. We previously found that phosphatidic acid (PA) binds Sec18 and thereby sequesters it from SNAREs and that PA dephosphorylation dissociates Sec18 from the membrane, allowing it to engage SNARE complexes. We now report that PA also induces conformational changes in Sec18 protomers and that hexameric Sec18 cannot bind PA membranes. Molecular dynamics (MD) analyses revealed that the D1 and D2 domains of Sec18 contain PA-binding sites and that the residues needed for PA binding are masked in hexameric Sec18. Importantly, these simulations also disclosed that a major conformational change occurs in the linker region between the D1 and D2 domains, which is distinct from the conformational changes that occur in hexameric Sec18 during SNARE priming. Together, these findings indicate that PA regulates Sec18 function by altering its architecture and stabilizing membrane-bound Sec18 protomers.",
author = "Starr, {Matthew L.} and Sparks, {Robert P.} and Arango, {Andres S.} and Hurst, {Logan R.} and Zhiyu Zhao and Muyun Lihan and Jenkins, {Jermaine L.} and Emad Tajkhorshid and Fratti, {Rutilio A.}",
note = "Funding Information: Acknowledgments—We thank Drs. Martin Gruebele, Shahar Suke-nik, Susan Martinis, and Zach Dayu for technical advice. Computational resources were provided by XSEDE (XSEDE MCA06N060) and Blue Waters (ACI-1440026). SPR was aided by the help of Dr. Jer-maine Jenkins at the University of Rochester Structural Biology & Biophysics Facility with support from National Institutes of Health NCRR Grant 1S10 RR027241, National Institutes of Health NIAID Grant P30AI078498, and the University of Rochester School of Medicine and Dentistry. Funding Information: This work was supported by National Institutes of Health Grants R01-GM101132 (to R. A. F.), and P41-GM104601, U01-GM111251, and U54-GM087519 (to E. T.), National Science Foundation Grant MCB 1818310 (to R. A. F.), and the Office of Naval Research ONR Grant N00014-16-1-2535 (to E. T.). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Publisher Copyright: {\textcopyright} 2019 Starr et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.",
year = "2019",
month = mar,
day = "1",
doi = "10.1074/jbc.RA118.006552",
language = "English (US)",
volume = "294",
pages = "3100--3116",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "9",
}