RT Journal Article SR Electronic(1) A1 Lim, Hyoun-Sub A1 Vaira, Anna Maria A1 Bae, Hanhong A1 Bragg, Jennifer N. A1 Ruzin, Steven E. A1 Bauchan, Gary R. A1 Dienelt, Margaret M. A1 Owens, Robert A. A1 Hammond, JohnYR 2010 T1 Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement JF Journal of General Virology, VO 91 IS 8 SP 2102 OP 2115 DO https://doi.org/10.1099/vir.0.019448-0 PB Microbiology Society, SN 1465-2099, AB Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.019448-0