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Title: AltMV TGB1 nucleolar localization requires homologous interaction and correlates with cell wall localization associated with cell-to-cell movement

item NAM, JIRYUN - Chungnam National University
item NAM, MOON - Chungnam National University
item BAE, HANHONG - Yeungnam University
item LEE, CHEOLHO - Seokyeong University
item LEE, BONG-CHUN - Rural Development Administration - Korea
item Hammond, John
item LIM, HYOUN-SUB - Chungnam National University

Submitted to: Plant Pathology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2013
Publication Date: 8/8/2013
Publication URL:
Citation: Nam, J., Nam, M., Bae, H., Lee, C., Lee, B., Hammond, J., Lim, H. 2013. AltMV TGB1 nucleolar localization requires homologous interaction and correlates with cell wall localization associated with cell-to-cell movement. Plant Pathology Journal . 29(4):454-459.

Interpretive Summary: Plant viruses cause significant disease losses in many crops; an understanding of the mechanisms of virus interactions with their hosts necessary for infection and systemic movement may lead to methods for interfering with the infection process, thus reducing losses to disease. The Triple Gene Block 1 (TGB1) protein of a potexvirus, Alternanthera mosaic virus, is required by the virus for multiple functions, including cell-to-cell movement and suppression of RNA silencing (a means of overcoming innate host plant resistance mechanisms). Examination of the homologous interactions between molecules of TGB1 and TGB1 mutants demonstrated that such self-interactions are necessary for efficient localization of the TGB1 protein to both the nucleolus and the cell wall, and that these interactions are important for functions of TGB1 in both cell-to-cell movement of the virus, and in RNA silencing suppression. This information will initially be of most interest to other scientists studying virus:host interactions and movement, and may eventually lead to development of methods to interfere with virus infection or systemic movement within infected plants.

Technical Abstract: The Potexvirus Alternanthera mosaic virus has multifunctional triple gene block (TGB) proteins, among which our studies have focused on the properties of the TGB1 protein. The TGB1 of AltMV has functions including RNA binding, RNA silencing suppression, and cell-to-cell movement, and is known to form homologous interactions. The helicase domains of AltMV TGB1 were separately mutated to identify which regions are involved in homologous TGB1 interactions. The yeast two hybrid system and Bimolecular Fluorescence Complementation in planta were utilized to examine homologous interactions of the mutants. Helicase motif I of AltMV TGB1 was found to be critical to maintain homologous interactions. Mutations in the remaining helicase motifs did not inhibit TGB1 homologous interactions. In the absence of homologous interaction of TGB1, subcellular localization of helicase domain I mutants showed distinctively different patterns from that of WT TGB1. These results provide important information to study viral movement and replication of AltMV.