Single-molecule micromanipulation studies of methylated DNA

Tetiana Zaichuk*, John F. Marko

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Cytosine methylated at the five-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 in the nanoscale length regime and demonstrated that cytosine methylation results in longer contour length and 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 flexibility and high structural stability of methylated DNA is likely to have significant consequences on the recruitment of proteins recognizing cytosine methylation and DNA packaging.

Original languageEnglish (US)
Pages (from-to)2148-2155
Number of pages8
JournalBiophysical Journal
Issue number11
StatePublished - Jun 1 2021

ASJC Scopus subject areas

  • Biophysics


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