Poster # 3
SINGLE-MOLECULE MICROMANIPULATION STUDIES OF METHYLATED DNA
Authors: Tetiana Zaichuk and John Marko, Northwestern University
Name: Tetiana Zaichuk
Affiliation: Northwestern University
Department: Molecular Biosciences
Advisor: John Marko
Advisor’s Email: firstname.lastname@example.org
NOTE: This poster will also be presented during the symposium Twitter Poster Session on the day of the symposium, Friday, October 30 between 9:00 – 11:30 AM (CT). Twitter posters will be available all day for viewing and interactive discussions. Posters will remain viewable on Twitter through the weekend from October 31-November 1.
Twitter Handle: @TZaichuk
Abstract: Cytosine methylated at the 5-carbon position is the most widely studied reversible DNA modification. Prior findings indicate that methylation can alter mechanical properties. However, those findings were qualitative and sometimes contradictory, leaving many aspects unclear. By applying single-molecule magnetic force spectroscopy techniques allowing for direct manipulation and dynamic observation of DNA mechanics and mechanically driven strand separation, we investigated how CpG and non-CpG cytosine methylation affects DNA micromechanical properties. We quantitatively characterized DNA stiffness using persistence length measurements from force-extension curves (FECs) in the nanoscale length regime and demonstrated that cytosine methylation results in increased DNA flexibility (i.e., decreased persistence length). In addition, we observed the preferential formation of plectonemes over unwound single-stranded “bubbles” of DNA, under physiologically relevant stretching forces and supercoiling densities. The stiffness and high structural stability of methylated DNA is likely to have significant consequences on the recruitment of proteins recognizing cytosine methylation and DNA packaging.
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