NMR study of human macroPARPs domains: 1H, 13C and 15N backbone and side-chain chemical shift assignments of hPARP9 macro domain 1 (MD1) in the apo and in the ADPr bound states

ADP-ribosylation is a reversible post-translational modification that regulates diverse cellular processes, including DNA damage repair, transcription, cell proliferation and innate immune responses, and is primarily catalyzed by members of the PARP family. While all 17 human PARPs contain a conserved C-terminal ADP-ribosyltransferase (ART) domain, only catalytically active members transfer ADP-ribose (ADPr) from nicotinamide adenine dinucleotide (NAD⁺) onto proteins or nucleic acids, and their N-terminal accessory domains, such as macro domains (MDs), WWE domains or RNA-binding motifs, mediate interactions that diversify PARP functions. Human PARP9 (hPARP9), known also as BAL1, is catalytically inactive due to sequence variations in catalytically important residues in the ART domain, but plays crucial roles in antiviral and antibacterial defense, stress responses and tumor progression through its heterodimeric interaction with the E3 ubiquitin ligase DTX3L. hPARP9 contains two tandem MDs (MD1 and MD2), with MD1 acting as a MacroD-type hydrolase "eraser" of mono-ADP-ribosylation (MARylation), while MD2 functions as an ADPr "reader". Their different role in the ADP-ribosylation pathway highlights the importance of structural and functional characterization for understanding ADPr-mediated cellular signaling. In this study, we report the NMR backbone and side-chain resonance assignments of hPARP9 MD1 in both apo and ADPr bound states. In addition, the secondary structure predictions using TALOS+ server and the Chemical Shift Perturbation (CSP) analysis upon ADPr binding are presented. The latter illustrates the MD substrate's accommodation mode and identifies the residues involved in ADPr binding, thus related to MDs' hydrolytic activity.