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Vault nanocapsule dissociation into halves triggered at low pH. | LitMetric

Vault nanocapsule dissociation into halves triggered at low pH.

Biochemistry

Chemical and Biomolecular Engineering Department, University of California, Los Angeles, California 90095, USA.

Published: March 2007

AI Article Synopsis

  • - Vaults are unique nanocapsules found in most eukaryotic cells, made of proteins and RNA, with their exact function still unknown but potentially useful in drug delivery and nanomaterials. - The study employed various methods, including fluorescence spectroscopy and multiangle laser light scattering (MALLS), to investigate how changing the solution's pH affected the structural conformation of these vaults, revealing that they become more open and may partially dissociate in acidic conditions. - Results from fluorescence intensity increases, MALLS data indicating changes in molecular mass and size, and transmission electron microscopy images confirmed that vaults disassemble into halves when the pH drops from 6.5 to 3.4.

Article Abstract

Vaults are self-assembled ribonucleoprotein nanocapsules that consist of multiple copies of three proteins (major vault protein, VPARP, and TEP1) and an untranslated RNA. Although their function has not been determined, vaults are found in nearly all eukaryotic cells. This study describes the use of fluorescence spectroscopy, multiangle laser light scattering (MALLS), and the quartz crystal microbalance (QCM) as tools in investigating recombinant vault conformational change in response to a varied solution pH. Identification of conditions for reversible vault disassembly and reassembly could enable application of these nanocapsules in drug delivery and in nanomaterials synthesis. Initial monitoring of changes in the intrinsic fluorescence intensity of vaults showed a 60% increase at pH 3.4 compared to that at pH 6.5, suggesting vaults exhibit a more open conformation at low pH. Fluorescence quenching studies provided further evidence of a vault structural change at low pH. MALLS data suggested a decrease in molecular mass accompanied by a clear increase in the radius of gyration as the solution pH was shifted from 6.5 to 3.4. This result prompted the hypothesis that vaults dissociate at least partially at low pH. Using the QCM to study adsorption of the vault onto self-assembled monolayers, data that suggest vault dissociation at low pH, even when the vault is in an adsorbed state, were also obtained. Finally, transmission electron microscopy (TEM) of negatively stained vaults at pH 6.5 and 3.4 confirmed the fluorescence spectroscopy, MALLS, and QCM findings by providing visual evidence that vaults disassemble into halves as the solution pH is lowered from 6.5 to 3.4.

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Source
http://dx.doi.org/10.1021/bi0606243DOI Listing

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