Yau-Heiu Hsu,2 and
1Institute of Biochemistry and 2Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 40227, Taiwan, Republic of China; 3Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China
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Accepted 5 July 2009.
The triple gene block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) is a transmembrane protein which is known to be required for the cell-to-cell movement of potexviruses. This protein has two conserved Cys residues, Cys-109 and Cys-112, at its C-terminal tail, which is supposed to be exposed on the outer surface of the endoplasmic reticulum (ER) membrane and ER-derived granular vesicles. In this study, we investigated the importance of these two Cys residues on the cell-to-cell and systemic movement of BaMV. Our results indicate that the Cys-to-Ala substitutions in TGBp2 make the cell-to-cell movement of BaMV relatively inefficient and the systemic movement of BaMV severely inhibited. Moreover, the defect in systemic movement is attributed to the inefficient transport of viral RNA in the phloem of petiole. Clearly, TGBp2 is critical not only for the cell-to-cell but also for the systemic movement of BaMV. In addition, the conserved Cys residues are important for the functioning of TGBp2.
© 2009 The American Phytopathological Society