This 2015 Italian study investigated effects of DNA methylation on mechanical properties of single DNA molecules:

“As a consequence of cytosine methylation, the binding of proteins that are implicated in transcription to gene promoters is severely hindered, which results in gene regulation and, eventually, gene silencing. To date, the mechanisms by which methylation biases the binding affinities of proteins to DNA are not fully understood; however, it has been proposed that changes in double-strand conformations, such as stretching, bending, and over-twisting, as well as local variations in DNA stiffness/flexibility may play a role.

We observe that methylation induces no relevant variations in DNA contour lengths, but produces measurable incremental changes in persistence lengths [stiffness/flexibility].

The results reported herein support the claim that the biological consequences of the methylation process, specifically difficulties in protein-DNA binding, are at least partially due to DNA conformation modifications.”

http://www.sciencedirect.com/science/article/pii/S0304416515002706 “Effects of cytosine methylation on DNA morphology: An atomic force microscopy study”