Life Science and Medical News from Around the Globe
Discovery of Chromosome Motor in Condensin Comlex Supports DNA Loop Extrusion Model for DNA Packaging in Cell Division
It is one of the great mysteries in biology: how does a cell neatly distribute its replicated DNA between two daughter cells? For more than a century, it has been known that DNA in the cell is comparable to a plate of spaghetti: a big jumble of intermingled strands. If a human cell wants to divide, it has to pack two meters of DNA into tidy little packages: chromosomes. This packing occurs using proteins called condensin, but how? When it comes to this question, scientists are split into two camps: the first argues that the protein works like a hook, randomly grasping somewhere in the jumble of DNA and tying it all together. The other camp thinks that the ring-shaped protein pulls the DNA inwards to create a loop. With an article published online on September 7, 2017 in Science, researchers from TU Delft, Heidelberg, and Columbia University give the “loop-extrustion camp” a significant boost: they demonstrate that condensin does indeed have the putative 'motor power' on board. The article is titled “The Condensin Complex Is a Mechanochemical Motor That Translocates Along DNA.” As early as 1882, the renowned biologist Walter Flemming recorded the process of “condensation” of DNA. Looking through a microscope, he saw how a cell neatly organized the bundles of DNA and subsequently divided them into two new cells. However, the exact details of this process have remained a mystery for more than 100 years.