Our cells perform engineering marvels when it comes to packing information into small spaces. Each time the cell divides, it assembles 4 meters of DNA into 46 small bundles, each a few millionths of a meter long. Researchers from EMBL Heidelberg and Julius-Maximilians-Universität Würzburg have now discovered how a family of DNA motor proteins manage to bundle loosely arranged DNA strands into compact individual chromosomes during cell division.
The researchers studied condensin, a protein complex necessary for chromosome formation. Although this compound was discovered more than three decades ago, its mode of action has remained largely unexplored. In 2018, researchers from Häring’s group at EMBL Heidelberg and their collaborators showed that condensation molecules create DNA loops, which may explain the formation of chromosomes. However, the internal procedures by which the protein complex achieves this feat remain unknown.
We have been working on this problem for a long time. But only now, by combining different experimental approaches, we have found an answer to this long-standing question,” said Christian Haring, former group leader at EMBL Heidelberg and now professor at Julius-Maximilians-Universität Würzburg.
Through precisely designed experiments, some of which ensure the unique condensation particles observation and processing While Forming loops of DNA, the researchers discovered how different parts of the complex collectively act as a molecular machine: one part keeps the DNA stable, like an anchor, while the other acts as a motor that pushes the DNA forward, creating a large loop.
Like other motor proteins, the condenser “steps” along the DNA, burning cellular energy in the form of ATP. However, these steps are more than 500 times longer than the steps taken by other DNA motor proteins, even though the amount of energy used is about the same. “It’s like a fuel-efficient Formula 1 race car for an e-bike,” said Indra Schaltel, first author of the study.
Sebastian Ostermann, group leader at EMBL Heidelberg and lead author of the study published in Science. “We can capture a working capacitor and derive the molecular choreography design of how ATP fuels its kinetic activity – a key step toward understanding DNA loop formation. Similar loops and their associated molecular machinery are involved in different genomic processes, including controlling how genes are turned on and off between divisions Cell.Therefore, our findings may have broader implications.
Condensers belong to one of the evolutionarily oldest families of chromosomal proteins. Thus, the discovery of this new mechanism opens up an entirely new field of study.
“It is possible that members of the class of motor proteins to which codonsin belongs are essential to all life on Earth,” Haring said. “It is clear that we are only just beginning to understand their roles and how they might be affected under human conditions.”
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