DNA in a cell can normally be compared to spaghetti on one’s plate: a large tangle of strands. To be able to divide DNA neatly between the two daughter cells during cell division, the cell organises this tangle into tightly packed chromosomes. A protein complex called condensin has been known to play a key role in this process, but biologists had no idea exactly how this worked. Until February 2018, when scientists from the Kavli Institute at Delft University of Technology, together with colleagues from EMBL Heidelberg, showed in real time how a condensin protein extrudes a loop in the DNA. Now, follow-up research by the same research groups shows that this is by no means the only way condensin packs up DNA. The researchers discovered an entirely new loop structure, which they call the 'Z loop'. They publish this new phenomenon on 4 March in Nature, where they show, for the first time, how condensins mutually interact to fold DNA into a zigzag structure. Read more