Replication is the greatest magic trick of nature. Watch carefully, and before your eyes you will see how one cell is blurred into two almost identical copies. Presto.
After more than half a century of research in the field of molecular genetics, it would have been easy to assume that we already have biological dexterity, but this is not so.
Now, using advanced technology, researchers have found important details showing how DNA multiplies its own replication.
“It was quite a mystery,” says molecular biologist David Gilbert of the University of Florida.
“Replication seemed to be resistant to everything we tried to do to break it. We described it in detail, showed that it changes in different types of cells and that it is disturbed by the disease. "
"But so far we have not been able to find this last element, controls, or DNA sequences that control it."
Open any tutorial on this topic, and you will see diagrams showing how long deoxyribonucleic acid (DNA) strands act as the world's longest puzzle, creating almost identical strands through the use of smart chemistry and many hardworking proteins.
Most of us have the luxury of camouflaging the details of this enzymatic magic to appreciate the whole trick.
But for researchers, the apparent complexity of this process, especially in organisms like us, mammals, proved to be a daunting task.
Like all good tricks, time is crucial. However, the disorder with regulatory proteins does not seem to matter as much as one would expect, indicating that the exact rhythm of replication is more associated with the DNA molecule acting on itself.
To uncover the chemical architecture that regulates DNA replication time, Gilbert and his team turned to a new technology, known as CRISPR, to grab mouse chromosomes to figure out which factors mattered.
CRISPR is a molecular tool based on a process that bacteria use to identify genes for threatening viruses. Once a specific genetic code has been discovered, CRISPR-related enzymes can sharpen and destroy the sequence, effectively eliminating the threat.
In the hands of researchers, the same system can be used to cut any designated DNA sequence.
Gilbert used it to target a variety of structures within the DNA architecture of mouse embryonic stem cells, switching them or cutting them out completely.
Initially, the focus was on protein binding sites, called the CCCTC-binding factor (CTCF). This protein helps regulate the entire transcription process, making its planting area a natural place to look for places that govern more space-time DNA operations.
However, interfering with them had little effect on the actual time of replication processes. Something else had to be at work.
However, finding this virtual needle in a haystack will require more than a little luck.
This was done in the form of a high-resolution, three-dimensional analysis of the contact areas that DNA made with itself. Thus, the team was able to determine which “fingertips” were in action.
In particular, they identified several key locations outside the boundaries associated with the CTFC. Breaking them caused chaos — replication time was chosen, the DNA architecture itself was weakened, and transcription was skipped.
“Removing these items shifted the segment replication time from the very beginning to the very end of the process,” says Gilbert.
"It was one of those moments when only one result knocks your socks off."
Their results open the way to new research on health and pathology. By identifying the mechanisms responsible for DNA replication, researchers can detect the processes that cause certain diseases.
“If you duplicate elsewhere and at another time, you can put together a completely different structure,” says Gilbert.
We have come a long way since physicist Erwin Schrödinger presented his prediction of an “aperiodic crystal” that could explain cell replication using a little more than basic chemistry physics.
More than seven decades later, molecular genetics physics is still reluctant to share its secrets.
Not that this makes the greatest magical show of nature less amazing.
This study was published in cell,