6d36

Publication Abstract from PubMed

ADP-ribosyl-acceptor hydrolase 3 (ARH3) plays important roles in regulation of poly(ADP-ribosyl)ation, a reversible post-translational modification, and in maintenance of genomic integrity. ARH3 degrades poly(ADP-ribose) to protect cells from poly(ADP-ribose)-dependent cell death, reverses serine mono(ADP-ribosyl)ation, and hydrolyzes O-acetyl-ADP-ribose, a product of Sirtuin-catalyzed histone deacetylation. ARH3 preferentially hydrolyzes O-linkages attached to the anomeric C1 of ADP-ribose; however, how ARH3 specifically recognizes and cleaves structurally diverse substrates remains unknown. Here, structures of full-length human ARH3 bound to ADP-ribose and Mg(2+), coupled with computational modeling, reveal a dramatic conformational switch from closed to open states that enables specific substrate recognition. The glutamate flap, which blocks substrate entrance to Mg(2+) in the unliganded closed state, is ejected from the active site when substrate is bound. This closed-to-open transition significantly widens the substrate-binding channel and precisely positions the scissile 1-O-linkage for cleavage while securing tightly 2- and 3-hydroxyls of ADP-ribose. Our collective data uncover an unprecedented structural plasticity of ARH3 that supports its specificity for the 1-O-linkage in substrates and Mg(2+)-dependent catalysis.

Structure of human ADP-ribosyl-acceptor hydrolase 3 bound to ADP-ribose reveals a conformational switch that enables specific substrate recognition.,Pourfarjam Y, Ventura J, Kurinov I, Cho A, Moss J, Kim IK J Biol Chem. 2018 Aug 10;293(32):12350-12359. doi: 10.1074/jbc.RA118.003586. Epub, 2018 Jun 15. PMID:29907568^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.