1H, 13C and 15N chemical shift assignments of Rubella virus macro domain in the free and in the ADPr bound state

Prokaryotes, eukaryotes, and certain viruses with positive single-stranded RNA genomes are among the forms of life that have been found to possess macro domains (MDs). There are claims that viral MDs inhibit the immune response mediated by PARPs, such as PARP12 and PARP14, and are involved in the formation of the viral replication transcription complex (RTC). Rubella virus (RuV) is included in this group of viruses. Its MD acts as an "eraser" of the posttranslation modification (PTM) ADP-ribosylation by binding to and hydrolyzing ADP-ribose (ADPr) from ADP-ribosylated substrates including proteins and nucleic acids. Consequently, it represents an attractive pharmacological target. Currently, no inhibitors exist for RuV MD's de-ADP-ribosylation activity, which may play a crucial role in viral replication and pathogenesis, as observed in severe acute respiratory syndrome coronavirus (SARS-CoV) and Chikungunya virus (CHIKV). RuV remains a serious threat, particularly to unvaccinated children, with approximately 10,000 of the 18,000 global cases in 2022 reported in Africa. Alarmingly, no FDA-approved drugs are available for RuV treatment. In this study, we present the almost complete NMR backbone and side-chain resonance assignment of RuV MD in both free and ADPr bound forms, along with the NMR chemical shift-based secondary structure element prediction. These findings will support the efficient screening of fragments or chemical libraries using NMR spectroscopy to identify compounds that are strong binders and potentially exhibit antiviral activity.