Barley stripe mosaic virus γb Protein Subverts Autophagy to Promote Viral Infection by Disrupting the ATG7-ATG8 Interaction

Autophagy is a conserved defense strategy against viral infection. However, little is known about the counterdefense strategies of plant viruses involving interference with autophagy. Here, we show that γb protein from Barley stripe mosaic virus (BSMV), a positive single-stranded RNA virus, directly...

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Bibliographic Details
Published in:The Plant cell 2018-07, Vol.30 (7), p.1582-1595
Main Authors: Yang, Meng, Zhang, Yongliang, Xie, Xialin, Yue, Ning, Li, Jinlin, Wang, Xian-Bing, Han, Chenggui, Yu, Jialin, Liu, Yule, Li, Dawei
Format: Article
Language:English
Subjects:
Accumulation
Antiviral activity
Autophagy
Barley
Disruption
Effectors
Infections
Nicotiana - metabolism
Nicotiana - virology
Pathogens
Phagocytosis
Plant Proteins - metabolism
Plant virus diseases
Plant viruses
Plant Viruses - genetics
Plant Viruses - metabolism
Plant Viruses - pathogenicity
Point mutation
Protein Binding
Proteins
Ribonucleic acid
RNA
RNA viruses
RNA, Viral - genetics
Viral infections
Viruses
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Summary:Autophagy is a conserved defense strategy against viral infection. However, little is known about the counterdefense strategies of plant viruses involving interference with autophagy. Here, we show that γb protein from Barley stripe mosaic virus (BSMV), a positive single-stranded RNA virus, directly interacts with AUTOPHAGY PROTEIN7 (ATG7). BSMV infection suppresses autophagy, and overexpression of γb protein is sufficient to inhibit autophagy. Furthermore, silencing of autophagy-related gene ATG5 and ATG7 in Nicotiana benthamiana plants enhanced BSMV accumulation and viral symptoms, indicating that autophagy plays an antiviral role in BSMV infection. Molecular analyses indicated that γb interferes with the interaction of ATG7 with ATG8 in a competitive manner, whereas a single point mutation in γb, Tyr29Ala (Y29A), made this protein deficient in the interaction with ATG7, which was correlated with the abolishment of autophagy inhibition. Consistently, the mutant BSMVY29A virus showed reduced symptom severity and viral accumulation. Taken together, our findings reveal that BSMV γb protein subverts autophagy-mediated antiviral defense by disrupting the ATG7-ATG8 interaction to promote plant RNA virus infection, and they provide evidence that ATG7 is a target of pathogen effectors that functions in the ongoing arms race of plant defense and viral counterdefense.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.18.00122