Physics is not the first scientific discipline that comes to mind when DNA is mentioned. However, scientists have discovered
What are telomeres and why are they the key to a long life?
Telomeres are the ends of chromosomes.They are characterized by the fact that they lack the ability to connect with other chromosomes or their fragments. In essence, they perform a protective function.
That is why they are considered the key to a long lifelife. They protect genes from damage, but they become slightly shorter each time a cell divides. If they become too short, the cell dies. The new discovery will help understand aging and disease.
Figure 1: Cell, chromosome and telomeres.
Credit: Fien Liflang/Leiden University
How do telomeres work?
Every cell in our body has chromosomes,which carry genes. They determine characteristics of the body, such as a person's appearance and susceptibility to certain diseases. At the ends of these chromosomes there are telomeres that protect them from damage. They are somewhat reminiscent of aiguillettes, plastic tips at the end of a lace.
The length of DNA between telomeres is two meters,therefore it must be rolled up to fit in the cage. This is achieved by wrapping DNA around “packets” of proteins; Together, DNA and proteins are called nucleosomes. They are organized into something like a bead, with a nucleosome, a piece of free (or unbound) DNA, a nucleosome, and so on.
Figure 2: Three different DNA structures.
Credit: Fien Liflang/Leiden University
This string of beads is then folded even further. How this happens depends on the length of the DNA between the nucleosomes, the beads on the string. Two structures that arise after folding were already known. In one of them, two adjacent beads stick together, and free DNA hangs between them (Fig. 2A ). If the DNA segment between the beads is shorter, adjacent beads do not have time to stick together. Two stacks are then formed next to each other (Figure 2B).
What have the scientists done?
In their study, Van Noort and colleaguesfound a different telomere structure. Here the nucleosomes are much closer together, so there is no longer any free DNA between the beads. This ultimately creates one large helix, or helix, of DNA (Figure 2C).
The new structure was discovered with the helpcombinations of electron microscopy and molecular force spectroscopy. In it, one end of the DNA is attached to a glass slide, and a tiny magnetic bead is attached to the other. A set of strong magnets above this ball separates the thread from the “beads”. By measuring the force required to pull one "bead" apart one after another, we can learn more about how the thread folds. The Singapore researchers then used an electron microscope to get a clearer picture of the structure.
What will the new discovery bring?
She is, according to scientists, the "holy grail"molecular biology". If biologists know the structure of molecules, it will give them more information about how genes are turned on and off. And also about how enzymes in cells interact with telomeres: for example, how they repair and copy DNA.
The discovery of a new telomeric structure will improveunderstanding the building blocks in the body. And this, in turn, will ultimately help study aging and diseases such as cancer, and develop drugs to combat them.
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