Ion-dependent conformational switching by a DNA aptamer that induces remyelination in a mouse model of multiple sclerosis

John Smestad, L. James Maher

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

We recently reported that a guanosine-rich 40-mer DNA aptamer (LJM-3064) mediates remyelination in the Theiler's murine encephalomyelitis virus mouse model of multiple sclerosis. Here, we characterize the G-quadruplex forms of this aptamer in vitro, and demonstrate using circular dichroism spectroscopy that LJM-3064 undergoes a monovalent ion-dependent conformational switch. In the presence of sodium ions and no potassium ions, LJM-3064 adopts an antiparallel-stranded G-quadruplex structure. When presented with low concentrations of potassium ions in a buffer that mimics the composition of interstitial fluid and blood plasma, LJM-3064 rapidly switches to a parallel-stranded G-quadruplex conformation, which is presumably the physiologically active folded form. We characterize these conformational states using dimethyl sulfate reactivity studies and Bal 31 nuclease probing. Our analysis indicates that only the 5′-terminal 26 nucleotides are involved in G-quadruplex formation. Thermodynamic characterization of LJM-3064 at physiologically relevant ion concentrations reveals the G-quadruplex to be metastable at human body temperature. These data provide important structural and thermodynamic insights that may be valuable in optimizing LJM-3064 as a therapeutic remyelinating agent.

Original languageEnglish (US)
Pages (from-to)1329-1342
Number of pages14
JournalNucleic acids research
Volume41
Issue number2
DOIs
StatePublished - Jan 1 2013

ASJC Scopus subject areas

  • Genetics

Fingerprint Dive into the research topics of 'Ion-dependent conformational switching by a DNA aptamer that induces remyelination in a mouse model of multiple sclerosis'. Together they form a unique fingerprint.

  • Cite this