Abstract
Alphaviruses are (re-)emerging arboviruses of public health concern. The nsP3 gene product is one of the key players during viral replication. NsP3 comprises three domains: a macro domain, a zinc-binding domain and a hypervariable region. The macro domain is essential at both early and late stages of the replication cycle through ADP-ribose (ADPr) binding and de-ADP-ribosylation of host proteins. However, both its specific role and the precise molecular mechanism of de-ADP-ribosylation across specific viral families remains to be elucidated. Here we investigate by X-ray crystallography the mechanism of ADPr reactivity in the active site of Getah virus macro domain, which displays a peculiar substitution of one of the conserved residues in the catalytic loop. ADPr adopts distinct poses including a covalent bond between the C′′1 of the ADPr and a conserved Togaviridae-specific cysteine. These different poses observed for ADPr may represent snapshots of the de-ADP-ribosylation mechanism, highlighting residues to be further characterised.
Highlights
Alphaviruses areemerging arboviruses of public health concern
The proteolysis intermediates and the final non-structural proteins (nsP) constitute the transcription/replication complex (TRC) organised in spherules at the plasma membrane. In this TRC, nsP3 has been for a long time the least understood nsP, but recent studies revealed some of its functions in viral r eplication3. nsP3 is organised into three domains: a macro domain (MD) at the N-terminal, a zinc-binding domain (ZBD) and a C-terminal hypervariable region (HVR)
The sequence corresponding to the putative macro domain on the Getah virus (GETV) nsp1234 sequence (GenBank reference ABK32031.1) is encompassing aa 1,333 to 1,492
Summary
Alphaviruses are (re-)emerging arboviruses of public health concern. The nsP3 gene product is one of the key players during viral replication. Members of the Alphavirus genus are geographically and evolutionary distinguished into “Old World” (OW) alphaviruses, represented by CHIKV, and “New World” (NW) viruses, prototyped by VEEV, as well as several species corresponding to viruses that most likely appeared from recombination events between OW and NW viruses[2] or viruses of marine origin Their genome is a positive-sense single-stranded RNA molecule which is usually 11 to 12 kilobases long. Like coronavirus or hepevirus macro domains[6,7], alphavirus macro domains recognise ADP-ribose and have de-ADP-ribosylation activity This latter functions are thought to be essential in both early and late replication steps[8]. The molecular mechanism of de-ADP-ribosylation by alphavirus macro domain remains to be clarified
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
