Alphavirus nsP3 ADP-ribosylhydrolase Activity Disrupts Stress Granule Formation

Aravinth Kumar Jayabalan; Diane E. Griffin; Anthony K. L. Leung

Given that the N-terminal MD possesses enzymatic activity to remove ADP-ribosylation [38, 45] and the structural integrity of SGs is dependent on ADP-ribosylation [19] , we hypothesized that the macrodomain of nsP3 (nsP3 MD ) could be responsible for suppressing SG formation. Similar to the fulllength nsP3, overexpression of the MD fragment (1-162) inhibited the formation of SGs upon treatment with arsenite (Fig. 1a , c) or other SG inducers, such as mitochondrial stressor clotrimazole and endoplasmic reticulum stressor thapsigargin (Fig. S1d , e; [9] ). However, unlike full-length nsP3, the nsP3 MD did not co-localize with G3BP1, presumably due to a lack of the G3BP-binding HVD (Fig. 1a) .