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Methylation is one of the most important epigenetic mechanisms in eukaryotes. 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. The present work investigates, at the single molecule level, the morphological consequences of DNA methylation in vitro. By tracking the atomic force microscopy images of single DNA molecules, we characterize DNA conformations pertaining to two different degrees of methylation. In particular, we observe that methylation induces no relevant variations in DNA contour lengths, but produces measurable incremental changes in persistence lengths. Furthermore, we observe that for the methylated chains, the statistical distribution of angles along the DNA coordinate length is characterized by a double exponential decay, in agreement with what is predicted for polyelectrolytes. 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.
This article was published in the following journal.
Name: Biochimica et biophysica acta
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Scanning microscopy in which a very sharp probe is employed in close proximity to a surface, exploiting a particular surface-related property. When this property is local topography, the method is atomic force microscopy (MICROSCOPY, ATOMIC FORCE), and when it is local conductivity, the method is scanning tunneling microscopy (MICROSCOPY, SCANNING TUNNELING).
A type of scanning probe microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. These deflections produce a topographic map of the sample.
A DNA (cytosine-5-)-methyltransferase that contains a central CxxC type zinc finger motif. It binds poly(ADP)-ribose and its expression is regulated by POLY (ADP-RIBOSE) POLYMERASE-1. DNMT1 methylates CpG residues, with a preference for hemimethylated DNA, and associates with DNA replication sites in S PHASE to maintain the methylation pattern in the newly synthesized strand, which is essential for EPIGENETIC PROCESSES. It also associates with CHROMATIN during G2 PHASE and MITOSIS to maintain DNA methylation independently of replication. It is responsible for maintaining methylation patterns established in development; mutations in the DNMT1 gene are associated with HEREDITARY SENSORY NEUROPATHY TYPE 1 class E.
Nanometer-sized tubes composed mainly of CARBON. Such nanotubes are used as probes for high-resolution structural and chemical imaging of biomolecules with ATOMIC FORCE MICROSCOPY.
Type of microscopy used to study biological systems at high resolution.
Bioinformatics is the application of computer software and hardware to the management of biological data to create useful information. Computers are used to gather, store, analyze and integrate biological and genetic information which can then be applied...
The development and maintenance of an organism is orchestrated by a set of chemical reactions that switch parts of the genome off and on at strategic times and locations. Epigenetics is the study of these reactions and the factors that influence them. ...