title: Structural and Mechanistic Analysis of the Slx1-Slx4 Endonuclease.
abstract: The SLX1-SLX4 endonuclease required for homologous recombination and DNA repair in eukaryotic cells cleaves a variety of branched DNA structures. The nuclease subunit SLX1 is activated by association with a scaffolding protein SLX4. At the present time, little is known about the structure of SLX1-SLX4 or its mechanism of action. Here, we report the structural insights into SLX1-SLX4 by detailing the crystal structure of Candida glabrata (Cg) Slx1 alone and in combination with the C-terminal region of Slx4. The structure of Slx1 reveals a compact arrangement of the GIY-YIG nuclease and RING domains, which is reinforced by a long α helix. Slx1 forms a stable homodimer that blocks its active site. Slx1-Slx4 interaction is mutually exclusive with Slx1 homodimerization, suggesting a mechanism for Slx1 activation by Slx4.
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Księcia Trojdena Street, 02-109 Warsaw, Poland.
authors.forename: Vineet
authors.initials: V
authors.lastname: Gaur
authors.affiliation: London Research Institute, Cancer Research UK, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK.
authors.forename: Haley D M
authors.initials: HDM
authors.lastname: Wyatt
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Księcia Trojdena Street, 02-109 Warsaw, Poland.
authors.forename: Weronika
authors.initials: W
authors.lastname: Komorowska
authors.affiliation: Biophysics Core Facility, International Institute of Molecular and Cell Biology, 4 Księcia Trojdena Street, 02-109 Warsaw, Poland.
authors.forename: Roman H
authors.initials: RH
authors.lastname: Szczepanowski
authors.affiliation: European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, CS 40220, 38043 Grenoble Cédex 9, France.
authors.forename: Daniele
authors.initials: D
authors.lastname: de Sanctis
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Księcia Trojdena Street, 02-109 Warsaw, Poland.
authors.forename: Karolina M
authors.initials: KM
authors.lastname: Gorecka
authors.affiliation: London Research Institute, Cancer Research UK, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: West
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Księcia Trojdena Street, 02-109 Warsaw, Poland. Electronic address: mnowotny@iimcb.gov.pl.
authors.forename: Marcin
authors.initials: M
authors.lastname: Nowotny