Co-Authors:
Chen, M.-H., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Tian, G.-W., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Gafni, Y., Department of Genetics, Agricultural Research Organization, Bet Dagan 50250, Israel
Citovsky, V., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Abstract:
Cell-to-cell tobacco mosaic virus movement protein (TMV MP) mediates viral spread between the host cells through plasmodesmata. Although several host factors have been shown to interact with TMV MP, none of them coresides with TMV MP within plasmodesmata. We used affinity purification to isolate a tobacco protein that binds TMV MP and identified it as calreticulin. The interaction between TMV MP and calreticulin was confirmed in vivo and in vitro, and both proteins were shown to share a similar pattern of subcellular localization to plasmodesmata. Elevation of the intracellular levels of calreticulin severely interfered with plasmodesmal targeting of TMV MP, which, instead, was redirected to the microtubular network. Furthermore, in TMV-infected plant tissues overexpressing calreticulin, the inability of TMV MP to reach plasmodesmata substantially impaired cell-to-cell movement of the virus. Collectively, these observations suggest a functional relationship between calreticulin, TMV MP, and viral cell-to-cell movement. © 2005 American Society of Plant Biologists.