“Dissecting the molecular trajectory of a eukaryotic Holliday junction-resolving enzyme”

Resolution of Holliday junctions in DNA requires the action of a nuclease that is selective for the structure of a four-way junction. The enzyme must introduce two precisely-positioned cleavages in a coordinated way. GEN1 is an important Holliday junction-resolving enzyme in eukaryotic cells, and is a member of the FEN/EXO family of nucleases. It binds to four-way junctions in dimeric form with nM affinity, and introduces bilateral cleavages of the DNA. Second strand cleavage is accelerated by 17-fold over the first, thereby ensuring productive resolution.

We have solved crystal structures of GEN1 bound to a Holliday junction and its product of resolution. We are dissecting the trajectory of the resolution process by a combination of structural and single-molecule biophysical approaches.

 

David M. J. Lilley FRS

University of Dundee