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In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth
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Minimal Reconstitution of Membranous Web Induced by a Vesicle-Peptide Sol-Gel Transition

James C S Ho1,2, Christoph Steininger1,2,3,4,5, Shu Hui Hiew1,2

  • 1Centre for Biomimetic Sensor Science , Nanyang Technological University , 50 Nanyang Drive 637553 , Singapore.

Biomacromolecules
|March 12, 2019
PubMed

Insights

Researchers identified key components for forming virus replication sites. A viral protein fragment and lipid vesicles create a gel-like condensate, mimicking the membranous web essential for RNA virus replication.

Area of Science:

  • Virology
  • Cell Biology
  • Biophysics

Background:

  • Positive-strand RNA viruses replicate within specialized cytoplasmic structures known as the membranous web.
  • These organelles, derived from the endoplasmic reticulum (ER), are formed by viral nonstructural protein NS4B, which induces lipid-protein condensates.
  • The exact physical mechanisms and minimal components driving membranous web formation remain incompletely understood.

Purpose of the Study:

  • To identify the minimal molecular and physical requirements for membranous web formation.
  • To elucidate the physical mechanisms underlying the self-assembly of these viral replication organelles.
  • To understand how viral proteins and host cell membranes interact to create specialized replication environments.

Main Methods:

  • In vitro reconstitution assays using purified viral protein domains and phospholipid vesicles.
  • Characterization of condensate properties, including viscoelasticity and molecular exchange dynamics.
  • Analysis of phase separation phenomena driven by peptide-vesicle interactions.

Main Results:

  • A minimal system comprising the N-terminal amphipathic domain of NS4B (peptide 4BAH2) and phospholipid vesicles (100-200 nm) was sufficient to form a gel-like, viscoelastic condensate.
  • This reconstituted condensate exhibited properties mirroring the virus-induced membranous web, including coexistence with an aqueous phase and rapid molecular exchange.
  • The study revealed that phospholipid vesicles act as supramolecular templates, organizing self-associating peptides to induce programmable multivalency and drive macroscopic phase separation.

Conclusions:

  • Membranous web formation is driven by a novel phase separation mechanism involving viral peptides and host phospholipid vesicles.
  • The N-terminal domain of NS4B plays a crucial role in condensate formation by interacting with lipid membranes.
  • This work provides a physical framework for understanding how viruses create specialized replication organelles through biomolecular phase separation.

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