News from CRG
At this very moment thousands of our body's cells are duplicating and dividing. This is the mechanism by which the body repairs damaged tissues and regenerates others like skin and hair. It involves a fairly complex process known as "mitosis", during which the cell duplicates its genetic material and separates it into two identical halves, which are then split apart. It is crucially important that this process works well each and every time it takes place, as otherwise it could give rise to mutations that might trigger diseases such as cancer.
Work published today in the Journal of Cell Biology and carried out by a team of researchers from the Centre for Genomic Regulation (CRG) sheds new and revealing light on this complex mechanism. In a study using yeast, they have discovered that an enzyme known to be vital for chromosome separation, topoisomerase 2 (Topo 2), is active for much longer than was previously thought; they have also observed that chromosome length is decisive in determining the amount of time this protein works for.
Mendoza explains that "surprisingly, we saw that the longer a chromosome is, the more time it takes the enzyme to unknot it completely. And we believe we understand why. As the speed at which these microtubules pull chromosomes apart is constant, when the chromosome is short, all the tangles or knots rapidly come under tension. On the other hand, if it is long, it will take more time for tension to spread through the whole chromosome", and, therefore, Topo 2 will finish to untangle them later. To understand this process better, just imagine someone trying to pick up and wrap a long rope.
Titos et al., Chromosome length and periuclear attachment constrain resolution of DNA intertwines. The Journal of Cell Biology (2014), http://doi.org/10.1083/jcb.201404039