Positive-strand RNA viruses induce the biogenesis of viral replication organelles (VROs), which support viral replication in infected cells. VRO formation requires viral replication proteins, co-opted host factors and intracellular membranes. Here, we show that the conserved Atg11 autophagy scaffold protein is co-opted by Tomato bushy stunt virus (TBSV) via direct interactions with the viral replication proteins. Deletion of ATG11 in yeast or knockdown of the homologous Atg11 in plants led to reduced tombusvirus replication, thus indicating pro-viral function for Atg11. Based on co-purification, BiFC and proximity-labeling experiments, we find that Atg11 is co-opted to stabilize virus-induced membrane contact sites (vMCS) within VROs. We propose that the tethering and scaffold function of Atg11 is critical in vMCSs for lipid enrichment. Absence of Atg11 interferes with sterols enrichment in VROs, rendering VROs RNAi-sensitive. Altogether, the expanding roles of co-opted host proteins with tethering functions suggest that the tombusvirus VROs are elaborate structures.
|Number of pages||16|
|State||Published - Jul 2022|
Bibliographical noteFunding Information:
The authors are grateful to Drs. Judit Pogany and Shifeng Zhu for helping the project and helpful discussions. The authors acknowledge the initial contribution by Dr. N. Kovalev to adapt the protein proximity labeling approach. The authors thank Dr. J. Weismann (UCSF) for providing plasmids pJW1506 and pJW1234. This work was supported by the National Science Foundation ( MCB-1517751 and IOS-1922895 ), USDA ( NIFA , 2020-70410-32901 ) and a USDA hatch grant ( KY012042 ) to PDN.
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