PMID:28735115

Citation	Cui, X, Yaghmaiean, H, Wu, G, Wu, X, Chen, X, Thorn, G and Wang, A (2017) The C-terminal region of the Turnip mosaic virus P3 protein is essential for viral infection via targeting P3 to the viral replication complex. Virology 510:147-155
Abstract	Like other positive-strand RNA viruses, plant potyviruses assemble viral replication complexes (VRCs) on modified cellular membranes. Potyviruses encode two membrane proteins, 6K2 and P3. The former is known to play pivotal roles in the formation of membrane-associated VRCs. However, P3 remains to be one of the least characterized potyviral proteins. The P3 cistron codes for P3 as well as P3N-PIPO which results from RNA polymerase slippage. In this study, we show that the P3N-PIPO of Turnip mosaic virus (TuMV) is required for viral cell-to-cell movement but not for viral replication. We demonstrate that the C-terminal region of P3 (P3C) is indispensable for P3 to form cytoplasmic punctate inclusions and target VRCs. We reveal that TuMV mutants that lack P3C are replication-defective. Taken together, these data suggest that the P3 cistron has two distinct functions: P3N-PIPO as a dedicated movement protein and P3 as an essential component of the VRC.
Links	PubMed Online version:10.1016/j.virol.2017.07.016
Keywords	DNA Mutational Analysis; Membrane Proteins/genetics; Membrane Proteins/metabolism; Plant Viral Movement Proteins/genetics; Plant Viral Movement Proteins/metabolism; Potyvirus/physiology; Tobacco; Viral Proteins/genetics; Viral Proteins/metabolism; Virus Release; Virus Replication
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
TUMVJ:MVP		GO:0046740: transport of virus in host, cell to cell	ECO:0000315:		P		Organism: Turnip mosaic virus (TuMV) protein is PIPO and is referred to as P3N-PIPO polyprotein in Uniprot. The mutant without PIPO was unable to move. "Confocal microscopy revealed that the PIPO knock-out mutant TuMV-GFP(∆PIPO) was contained in a single cell and lost the ability to move to the neighboring cells 4 days post agroinfiltration (dpa) (Fig. 1B)."Figure 1B clearly shows that transport of the virus from cell to cell is stopped by loss of P3 meaning that P3 is necessary for transport of virus in host from cell to cell. Host: Nicotiana benthamiana	complete CACAO 12987
TUMVJ:POLG		GO:0009405: pathogenesis	ECO:0000315:		P		organism: Turnip mosaic virus Protein is P3 in the paper. P3 in polyprotein POLG (Uniprot)."TuMV-GFP showed typical mosaic and leaf curling symptoms in upper new leaves, while the corresponding leaves in those inoculated by TuMV-GFP(∆GDD) and TuMV-GFP(∆P3C) did not display any symptoms (Fig. 2B)." Host: N. benthamiana	complete CACAO 13046
TUMVJ:POLG		GO:0039690: positive stranded viral RNA replication	ECO:0000315:		P		The organism is Turnip mosaic virus and the protein is P3 in the paper. P3 in polyprotein POLG (Uniprot). Fig 3 shows that the delta P3 is deficient in positive stranded RNA viral replication after 24 hours compared to the wild type virus "The P3C deletion mutant showed slightly higher levels of (+) and (−) viral RNAs than the replication-defective mutant TuMV-GFP(∆GDD) at both time points (Fig. 3) with a significant difference (P<0.05) only found between the (+) viral RNA levels of the P3C deletion"	complete CACAO 13047

References

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