%0 Journal Article %A Gushchin, Vladimir A. %A Lukhovitskaya, Nina I. %A Andreev, Dmitri E. %A Wright, Kathryn M. %A Taliansky, Michael E. %A Solovyev, Andrey G. %A Morozov, Sergey Y. %A MacFarlane, Stuart A. %T Dynamic localization of two tobamovirus ORF6 proteins involves distinct organellar compartments %D 2013 %J Journal of General Virology, %V 94 %N 1 %P 230-240 %@ 1465-2099 %R https://doi.org/10.1099/vir.0.045278-0 %I Microbiology Society, %X ORF6 is a small gene that overlaps the movement and coat protein genes of subgroup 1a tobamoviruses. The ORF6 protein of tomato mosaic virus (ToMV) strain L (L-ORF6), interacts in vitro with eukaryotic elongation factor 1α, and mutation of the ORF6 gene of tobacco mosaic virus (TMV) strain U1 (U1-ORF6) reduces the pathogenicity in vivo of TMV, whereas expression of this gene from two other viruses, tobacco rattle virus (TRV) and potato virus X (PVX), increases their pathogenicity. In this work, the in vivo properties of the L-ORF6 and U1-ORF6 proteins were compared to identify sequences that direct the proteins to different subcellular locations and also influence virus pathogenicity. Site-specific mutations in the ORF6 protein were made, hybrid ORF6 proteins were created in which the N-terminal and C-terminal parts were derived from the two proteins, and different subregions of the protein were examined, using expression either from a recombinant TRV vector or as a yellow fluorescent protein fusion from a binary plasmid in Agrobacterium tumefaciens. L-ORF6 caused mild necrotic symptoms in Nicotiana benthamiana when expressed from TRV, whereas U1-ORF6 caused severe symptoms including death of the plant apex. The difference in symptoms was associated with the C-terminal region of L-ORF6, which directed the protein to the endoplasmic reticulum (ER), whereas U1-ORF6 was directed initially to the nucleolus and later to the mitochondria. Positively charged residues at the N terminus allowed nucleolar entry of both U1-ORF6 and L-ORF6, but hydrophobic residues at the C terminus of L-ORF6 directed this protein to the ER. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.045278-0