Preparation and crystallization of human flap endonuclease FEN-1 in complex with proliferating-cell nuclear antigen, PCNA.

Flap endonuclease-1 (FEN-1) is a structure-specific nuclease that removes 5'-overhanging flaps in DNA repair and replication. FEN-1 binds proliferating-cell nuclear antigen (PCNA), a DNA-clamp protein, when processing Okazaki fragments during lagging-strand DNA synthesis. Here, the crystallization of the complex between human FEN-1 and PCNA is reported. The crystals were found to belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 82.2, b = 143.4, c = 246.7 A, and contained one complex in the crystallographic asymmetric unit. A diffraction data set was collected to a resolution of 3.0 A.