Ion-dependent conformational switching by a DNA aptamer that induces remyelination in a mouse model of multiple sclerosis. Nucleic Acids Res 2013 Jan;41(2):1329-42
Date
11/24/2012Pubmed ID
23175609Pubmed Central ID
PMC3553947DOI
10.1093/nar/gks1093Scopus ID
2-s2.0-84875458259 (requires institutional sign-in at Scopus site) 27 CitationsAbstract
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.
Author List
Smestad J, Maher LJ 3rdAuthor
John Smestad PhD, BS, MD Assistant Professor in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsAptamers, Nucleotide
Cations
Disease Models, Animal
G-Quadruplexes
Mice
Multiple Sclerosis
Potassium
Sodium
Thermodynamics
