NbRABG3f, a member of Rab GTPase, is involved in Bamboo mosaic virus infection in Nicotiana benthamiana

Abstract

The screening of differentially expressed genes in plants after pathogen infection can uncover the potential host factors required for the pathogens. In this study, an up-regulated gene was identified and cloned from Nicotiana benthamiana plants after Bamboo mosaic virus (BaMV) inoculation. The up-regulated gene was identified as a member of the Rab small guanosine triphosphatase (GTPase) family, and was designated as NbRABG3f according to its in silico translated product with high identity to that of RABG3f of tomato. Knocking down the expression of NbRABG3f using a virus-induced gene silencing technique in a protoplast inoculation assay significantly reduced the accumulation of BaMV. A transiently expressed NbRABG3f protein in N. benthamiana plants followed by BaMV inoculation enhanced the accumulation of BaMV to approximately 150%. Mutants that had the catalytic site mutation (NbRABG3f/T22N) or had lost their membrane-targeting capability (NbRABG3f/ΔC3) failed to facilitate the accumulation of BaMV in plants. Because the Rab GTPase is responsible for vesicle trafficking between organelles, a mutant with a fixed guanosine diphosphate form was used to identify the donor compartment. The use of green fluorescent protein (GFP) fusion revealed that GFP-NbRABG3f/T22N clearly co-localized with the Golgi marker. In conclusion, BaMV may use NbRABG3f to form vesicles derived from the Golgi membrane for intracellular trafficking to deliver unidentified factors to its replication site; thus, both GTPase activity and membrane-targeting ability are crucial for BaMV accumulation at the cell level.

Enrichment of Phosphatidylethanolamine in Viral Replication Compartments via Co-opting the Endosomal Rab5 Small GTPase by a Positive-Strand RNA Virus

“…Although the proviral functions of plant Rab small GTPases have not yet been defined in detail, the role of the Golgi-localized NbRABG3f is important for Bamboo mosaic virus replication [ 53 ]. Also, Arf1 small GTPase binds to the p27 replication protein of Red clover necrotic mosaic virus , and inhibition of Arf1 activity disrupted VRC assembly [ 54 ].…”

Perception of double‐stranded RNA in plant antiviral immunity

“…Typically, plant virus replication on membranes induces strong membrane modifications and is associated with interference of virus infection with lipid metabolism and membrane targeting and transport (Altan-Bonnet, 2017;De Castro et al, 2013;Nagy, 2016;Nagy and Pogany, 2012;Zhang et al, 2016aZhang et al, , 2018. Infection by diverse plant viruses has been shown to imply membrane fusion processes (Garcia Cabanillas et al, 2018;Huang et al, 2015;Wei et al, 2013) as well as conventional and unconventional protein transport routes (Diaz et al, 2015;Grangeon et al, 2012;Kovalev et al, 2016;Movahed et al, 2019;Ribeiro et al, 2008;Wang et al, 2011;Wei and Wang, 2008).…”

Host Factors in the Infection Cycle of Bamboo mosaic virus

“…NbRabG3f was demonstrated to be a positive regulator in BaMV replication by loss- and gain-of-function assays (Huang et al, 2016). Rabs are a group of small GTPases involved in vesicles transport, uncoating, tethering, and fusion (Seabra et al, 2002).…”