Look deeper into DNA, examine how building blocks stack together!

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DNA, the genetic blueprint for all living cells, is made up of four nucleotide bases: Adenine (A), Guanine (G), Thymine (T), and Cytosine (C). These bases form pairs, with A pairing with T and G with C, creating the double-stranded structure of DNA. The stability of this double helix is maintained through two types of interactions: base-pairing and base-stacking. According to Mahipal Ganji, an Assistant Professor at the Department of Biochemistry, IISc, base-stacking interactions, which are generally stronger than base-pairing, can be compared to the teeth of a zipper, ensuring a secure connection.

 

To study the 16 possible base-stacking combinations, researchers used a novel imaging technique called DNA-PAINT (Point Accumulation in Nanoscale Topography). This method involves the random binding and unbinding of two artificially designed DNA strands in a buffer solution at room temperature. Each strand ends with a different base and is tagged with a fluorophore that emits light when binding occurs. The binding and unbinding events were captured as images under a fluorescence microscope.


FIG: Patterned DNA nanostructures (cyan) as imaged using DNA-PAINT super-resolution technique enabled for studying strength of base-stacking interactions (pink).


The researchers found that the time required for the strands to bind and unbind increased with stronger base-stacking interactions. Using this data, they developed a model that links the timing of binding and unbinding with the strength of the interaction between stacked bases. This innovative technique provided new insights into base-stacking. For example, adding just one more base-stacking interaction to a DNA strand could increase its stability by up to 250 times. Additionally, each nucleotide pair showed unique stacking strengths, allowing the design of highly efficient three-armed DNA nanostructures.

REFRENCE: https://www.indiatoday.in/science/story/indian-scientists-look-deeper-into-dna-examine-how-building-blocks-stack-together-2423062-2023-08-18


Behind "The Biotechnology Journal"
Mansi Popat & Japan Raval


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