N-terminal acetylation of the βC1 protein encoded by the betasatellite of tomato yellow leaf curl China virus is critical for its viral pathogenicity

Abstract

N-terminal acetylation (N-acetylation) is one of the most common protein modifications and plays crucial roles in viability and stress responses in animals and plants. However, very little is known about N-acetylation of viral proteins. Here, we identified the Thr residue at position 2 (Thr-2) in the βC1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-βC1) as a novel N-acetylation site. Furthermore, the effects of TYLCCNB-βC1 N-acetylation on its function as a pathogenicity factor were determined via N-acetylation mutants in Nicotiana benthamiana plants. We found that N-acetylation of TYLCCNB-βC1 is critical for its self-interaction in the nucleus and viral pathogenesis, and that removal of N-acetylation of TYLCCNB-βC1 attenuated tomato yellow leaf curl China virus-induced symptoms and led to accelerated degradation of TYLCCNB-βC1 through the ubiquitin-proteasome system. Our data reveal a protective effect of N-acetylation of TYLCCNB-βC1 on its pathogenesis and demonstrate an antagonistic crosstalk between N-acetylation and ubiquitination in this geminiviral protein.