PMID: 26686639

Authors:

Liu Y, Freeman AD, Declais AC, Wilson TJ, Gartner A, Lilley DM

Title:

Crystal Structure of a Eukaryotic GEN1 Resolving Enzyme Bound to DNA.

Journal:

Cell Rep. 2015 Dec 22;13(11):2565-75. doi: 10.1016/j.celrep.2015.11.042. Epub, 2015 Dec 10.

Abstract:

We present the crystal structure of the junction-resolving enzyme GEN1 bound to DNA at 2.5 A resolution. The structure of the GEN1 protein reveals it to have an elaborated FEN-XPG family fold that is modified for its role in four-way junction resolution. The functional unit in the crystal is a monomer of active GEN1 bound to the product of resolution cleavage, with an extensive DNA binding interface for both helical arms. Within the crystal lattice, a GEN1 dimer interface juxtaposes two products, whereby they can be reconnected into a four-way junction, the structure of which agrees with that determined in solution. The reconnection requires some opening of the DNA structure at the center, in agreement with permanganate probing and 2-aminopurine fluorescence. The structure shows that a relaxation of the DNA structure accompanies cleavage, suggesting how second-strand cleavage is accelerated to ensure productive resolution of the junction.