%0 Journal Article %A Jijin R. A. Kuttiyatveetil %A Heddy Soufari %A Morgan Dasovich %A Isabel R. Uribe %A Shang-Jung Cheng %A Anthony K. L. Leung %A John M. Pascal %T Crystal structures and functional analysis of the ZnF5-WWE1-WWE2 region of PARP13/ZAP define a new mode of engaging poly(ADP-ribose) %D 2021 %R 10.1101/2021.12.15.472832 %J bioRxiv %P 2021.12.15.472832 %X PARP13/ZAP acts against multiple viruses through recognizing and promoting degradation of cytoplasmic viral mRNA. PARP13 has four N-terminal Zn-finger motifs that bind CG-rich nucleotide sequences, and a C-terminal ADP ribosyltransferase fold similar to other PARPs. A central region predicted to contain a fifth Zn-finger and two tandem WWE domains is implicated in binding poly(ADP-ribose); however, there are limited insights into the structure and function of this PARP13 region (ZnF5-WWE1-WWE2). Here, we present crystal structures of ZnF5-WWE1-WWE2 from mouse PARP13 in complex with ADP-ribose and with ATP. ZnF5-WWE1-WWE2 crystallized as a dimer with major contacts formed between WWE1 and WWE2 originating from different monomers, indicative of a more compact monomeric arrangement of the tandem WWE domains. Solution scattering experiments and biophysical analysis indicated a monomer in solution, suggesting that the crystal dimer represents domain swapping that could potentially represent a PARP13 conformation assumed when signaling viral RNA detection. The crystal structure and binding studies demonstrate that WWE2 interacts with ADP-ribose and ATP, whereas WWE1 does not have a functional binding site. The shape of the WWE2 binding pocket disfavors interaction with the ribose-ribose linkage of poly(ADP-ribose). Binding studies with poly(ADP-ribose) ligands indicate that WWE2 serves as an anchor for preferential binding to the terminal end of poly(ADP-ribose), and the composite structure of ZnF5-WWE1-WWE2 forms an extended surface to engage polymer chains of ADP-ribose. This model represents a novel mode of poly(ADP-ribose) recognition and provides a structural framework for investigating poly(ADP-ribose) impact on PARP13 function.Competing Interest StatementThe authors have declared no competing interest. %U https://www.biorxiv.org/content/biorxiv/early/2021/12/16/2021.12.15.472832.full.pdf