For the very first time, scientists announce the observance of the intercalated motif DNA structure in human cells.
When most people think of human DNA, they usually picture the classic double helix structure discovered by James Watson and Francis Crick in 1953.
However, there are plenty of other DNA structures which naturally occur within the human body.
Other forms, such as A-DNA, Z-DNA, triplex DNA and Cruciform DNA all exist (or theoretically exist) within the human body to help us transmit information and genetic code.
The intercalated motif is a similar kind of DNA which, until now, was only ever seen in in-vitro testing. This is the first time that this form of DNA structure has been seen within living human cells.
“When most of us think of DNA, we think of the double helix,” said Daniel Christ, a member of the research team from the Garvan Institute of Medical Research in Australia.
“This new research reminds us that totally different DNA structures exist – and could well be important for our cells.”
Originally discovered in the 1990s, the intercalated motif structure is one of the most elusive DNA structures of recent years. Now, however, this recent discovery sheds light on the structure and its uses within the human body.
“the i-motif is a four-stranded ‘knot’ of DNA,” Co-leader of the research project, Michael Dinger, explained: “In the knot structure, C [cytosine] letters on the same strand of DNA bind to each other – so this is very different from a double helix, where ‘letters’ on opposite strands recognise each other, and where Cs bind to Gs [guanines].”
This form of knot structure could be entirely different in its function and properties to the conventional double helix shape.
The intercalated motif is also not the first DNA structure discovered in this way. G-quadruplex (G4) DNA was first observed in human cells in 2013. This allowed researchers to develop an engineered antibody to reveal the G4 within human cells.
In this study, the research team employed the same kind of technique by developing a form of antibody fragment called iMab that can recognize and bind to intercalated motifs.
While not everything is known about how the intercalated motif structure works, findings indicate that transient intercalated motifs often form late in the life cycle of a cell.
This form of DNA structure also tends to be in ‘promoter’ regions. These are areas of DNA that control if genes are switched on or off. They are also sometimes found in telomeres, which are genetic markers associated with aging.
Now that this new form of DNA is known to exists in cells, it will give researchers further drive to discover exactly what role this structure plays within our bodies.
The findings of this research project can be found in the journal Nature Chemistry.