Research review urges further study of condensins and cohesins - nature's bobby pins

There are structures inside your cells that can (and do) automatically organize your DNA. Proteins called condensins and cohesins are analogous to bobby pins with a hinge at one end and the ability to open and close alternating between a V-shape or pin conformation. These proteins tether different DNA locations together within the same molecule, creating loops and nested loops that organize and compact your DNA. 

Robert V. Skibbens highlighted the functions of these proteins in a study published in the Journal of Cell Science in February 2019. His review of research looks into how condensins and cohesins work, and how they differ.

Condensins and cohesins keep parts of the DNA that cells need easily accessible, and the parts that aren’t so high need they keep tucked away. These proteins allow DNA to be copied and separated without breaking the strands of DNA.

Condensins and cohesins work at different points in the cell cycle.  Condensins densely pack the chromosomes during the cell division process. Cohesins organize the chromosome during interphase when the cell needs rapid access to many different parts of DNA.  

Condensins and cohesins are also structurally distinct.  When visualized under an electron microscope, cohesins have a visible space where a strand of DNA could be entrapped. Condensins don’t have this visible space, but they have a minimum of two DNA binding sites. One of those sites connects to a region of DNA, and the other site allows the DNA loop to grow by pumping it.

Although models have been proposed, a complete picture for how these molecular bobby-pin-like proteins function remains unclear since most current research requires separation of these proteins from their native cellular environment which may affect their function.

Skibbens urges further study of how these proteins work because they appear to be different, and there are many questions that still need to be answered.