Can we live longer? Physicist’s Groundbreaking Discovery in the Genetic Protective Layer

Researchers have discovered a new telomeric DNA structure, which could be the key to living longer.

Researchers have discovered a new telomere structure DNA using physics and a small magnet. Telomeres are considered by many scientists to be the key to living longer. They protect genes from damage but shorten a bit each time a cell divides. If they get too short, the cell dies. This groundbreaking discovery will help us understand aging and disease.

When you hear of DNA, physics is usually not the first scientific discipline that comes to mind. However, John van Noort from the Leiden Institute of Physics (LION) in the Netherlands is one of the scientists who discovered the new structure of DNA. As a biophysicist, he uses methods from physics for biological experiments. It also caught the attention of biologists at Nanyan Technological University in Singapore, who asked him to help study the DNA structure of telomeres. They published the results on September 14 in the scientific journal Nature.

Pearl necklace

Every cell in our body contains chromosomes that carry genes that determine our characteristics (how we look, for example). At the ends of these chromosomes are telomeres, which protect the chromosomes from damage. It’s a bit like aiguillettes, the plastic tips at the end of the laces.

Cell, chromosome and telomeres

Figure 1: A cell, a chromosome and telomeres. Credit: University of Leiden

Because the DNA between telomeres is two meters long, it must be bent to fit in a cell. This is achieved by wrapping DNA around protein bundles. Together, DNA and proteins form a nucleosome. These are arranged in something similar to a string of beads, with a nucleosome, a piece of free (or unbound) DNA, a nucleosome, etc.

This string of beads then folds up even more. How it depends on the length of the DNA between the nucleosomes, the beads on the chain. Two structures that occur after folding were already known. In one of them, two adjacent beads stick together and free DNA is suspended between them (Figure 2A). If the piece of DNA between beads is shorter, adjacent beads fail to stick together. Then two stacks form side by side (Figure 2B).

In their study, Van Noort and his colleagues discovered another telomere structure. Here, the nucleosomes are much closer together, so there is no more free DNA between the beads. This ultimately creates a large helix, or spiral, of DNA (Figure 2C).

Three different DNA structures

Figure 2: The three different DNA structures. Credit: University of Leiden

Magnet

The new structure was discovered using a combination of electron microscopy and molecular force spectroscopy. This last technique comes from the laboratory of Van Noort. Here, one end of the DNA is attached to a glass slide and a small magnetic ball is stuck to the other. A set of strong magnets above this ball then separates the pearl necklace. By measuring the force needed to pull the beads apart one at a time, you will know more about how the string is bent. The Singapore researchers then used an electron microscope to get a better picture of the structure.

building blocks

Structure, says Van Noort, is “the holy grail of molecular biology”. If we know the structure of molecules, it will allow us to better understand how genes are turned on and off and how enzymes in cells deal with telomeres: how they repair and copy DNA, for example. The discovery of the new telomeric structure will improve our understanding of the building blocks of the body. And it will ultimately help us study aging and diseases like cancer and develop drugs to fight them.

Illustration of telomeres

A telomere is a region of repetitive DNA sequences at the end of a chromosome. Telomeres prevent the ends of chromosomes from fraying or tangling. Each time a cell divides, the telomeres become slightly shorter. Eventually they become so short that the cell can no longer divide successfully and the cell dies. Credit: National Institute for Human Genome Research, NIH

Reference: “Columnar structure of human telomeric chromatin” by Aghil Soman, Sook Yi Wong, Nikolay Korolev, Wahyu Surya, Simon Lattmann, Vinod K. Vogirala, Qinming Chen, Nikolay V. Berezhnoy, John van Noort, Daniela Rhodes and Lars Nordenskiöld, September 14, 2022, Nature.
DOI: 10.1038/s41586-022-05236-5

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