What do you picture in mind when you think of DNA? Probably a double helix, right? But a new research upends everything we know about living cells. Apparently, the double helical structure isn’t the only form of DNA which exists in human cells.
A newly identified structure which looks like a “twisted knot” in DNA is quite different from the double helix that was found in the year 1953. This never-before-seen genetic material can play a significant role in the translation of genes.
While this DNA bit dubbed as intercalated motif (i-motif) was discovered way back in the ’90s, but it’s the first time when scientists have observed it in living bodies outside the test tubes.
The findings of this study from the Garvan Institute of Medical Research, published in the journal Nature Chemistry, describes the i-motifs as a four-stranded ‘knot’ of DNA.
According to the Australian researchers, not only the i-motifs exists in human bodies, but they are quite common too. In fact, these structures play a crucial role in cell biology.
As we know, the double helix nitrogen bases of adenine (A) with thymine (T) and cytosine (C) with guanine (G), form base pairs that are stacked on top of one another within two phosphate strands that twist around to form a spiral ladder.
But this new DNA structure occurs as a knot within the helical strands, where C binds to C instead of G. Another striking characteristic was the ability of i-motifs to fold and unfold the knots based upon the level of acidity in their surroundings.
These structures were mostly found in areas of the genome which is responsible for deciding whether or not a certain gene gets expressed. Hence, scientists believe that i-motifs are some kind of switch that helps in turning the genes on or off.
Although they are quite difficult to track down due to their transient nature, this discovery proffers a whole new level of insight on DNA which might help in unraveling the greater mysteries of our genetic codes.