NMR study of human macroPARPs domains: 1H, 15N and 13C resonance assignment of hPARP14 macro domain 2 in the free and the ADPr bound state.

hPARP14 is a human ADP-ribosyl-transferase (ART) that belongs to the macroPARPs family, together with hPARP9 and hPARP15. It contains a tandem of three macro domains (MD) while each of them has different properties. The first one, namely MD1, has not been reported to exhibit a high binding affinity for ADP-ribose (ADPr) in contrast to the following two (MD2 and MD3). All three MDs exhibit an α/ß/α sandwich-like fold as reported by the deposited crystallographic structures. MD2 and MD3 recognize mono-ADP-ribosylated (MARylated) but not poly-ADP-ribosylated (PARylated) substrates and thus they allow hPARP14 to bind its targets, which can be potentially MARylated by its catalytic domain (CD). hPARP14 participates in DNA damage repair process and immune response against viruses like SARS-CoV-2, which also harbors an MD fold. Furthermore, hPARP14 like the other two macroPARPs (hPARP9 and hPARP15), is implicated in numerous types of cancer, such as B-aggressive lymphoma and sarcoma, rendering its MDs as potential important drug targets. Herein, we report the complete NMR backbone and side chain assignment (1H, 13C, 15N) of hPARP14 MD2 in the free and ADPr bound states and the NMR chemical shift-based prediction of its secondary structure elements. This is the first reported NMR study of a hPARP macro domain, paving the way to screen by NMR chemical compounds which may alter the ability of hPARP14 to interact with its substrates affecting its function.

NMR study of macro domains (MDs) from betacoronavirus: backbone resonance assignments of SARS-CoV and MERS-CoV MDs in the free and the ADPr-bound state.

SARS-CoV and MERS-CoV Macro Domains (MDs) exhibit topological and conformational features that resemble the nsP3b macro (or "X") domain of SARS-CoV-2. Indeed, all the three domains (SARS-CoV-2, SARS-CoV and MERS-CoV MDs) fold in a three-layer α/ß/α sandwich structure, as reported by crystallographic structural investigation of SARS-CoV MD and MERS-CoV MD. These viral MDs are able to bind ADP-ribose as many other MDs from different kingdoms. They have been characterized also as de-ADP-ribosylating enzymes. For this reason, these viral macrodomains recently emerged as important drug targets since they can counteract antiviral ADP-ribosylation mediated by poly-ADP-ribose polymerase (PARPs). Even in presence of the 3D structures of SARS-CoV MD and of MERS-CoV MD, we report herein the almost complete NMR backbone (1H, 13C, 15N) of SARS-CoV MD and MERS-CoV proteins in the free and ADPr bound forms, and the NMR chemical shift-based prediction of their secondary structure elements. These NMR data will help to further understanding of the atomic-level conformational dynamics of these proteins and will allow an extensive screening of small molecules as potential antiviral drugs.