Uncovering the inner workings of the molecular machinery that shapes chromosomes during cell division

When it comes to packing information into small spaces, our cells do a great job. Each time a cell divides, it bundles up 4 meters of DNA into 46 tiny packages, each of which is less than a millionth of a meter in length. Researchers from the Julius-Maximilians-Universitt Wrzburg have discovered how a family of DNA motor proteins works.

The researchers studied how condensin works. More than three decades have passed since this complex was discovered. Researchers from the Hring group at EMBL were able to show that condensin molecule create loops of DNA, which could explain how chromosomes are formed. The inner workings of theprotein complex were not known.

The problem has been worked on for a long time. Christian Hring, a professor at the Julius-Maximilians-Universitt Wrzburg, said that they have found an answer to the question.

The researchers were able to observe and manipulate single condensin molecule while they were in the process of forming DNA loops, as well as find out how different parts of the complex collectively act as amolecular machines.

condensin burns cellular energy in the form ofATP while taking steps along the DNA. The amount of energy used is roughly the same, but the steps taken by these genes are 500 times longer. Indra Shaltiel said it was like a formula one racing car with an e-bike.

Sebastian Eustermann is a senior author of the study that was published in Science. It was possible to capture condensin in action and derive a sequence of how ATP fuels its motor activity. The control of how genes are switched on and off in between cells has been implicated in loops and related machines. Our findings could have even broader implications.

One of the most ancient families of genes is the condensations. A new field of study has been opened up by the discovery of this new mechanism. Hring said that members of the class of motor proteins condensin are essential for all life on Earth. We are only just beginning to understand their roles and how they may be affected in human conditions.

More information: Indra A. Shaltiel et al, A hold-and-feed mechanism drives directional DNA loop extrusion by condensin, Science (2022). DOI: 10.1126/science.abm4012 Journal information: Science