Journal of General Virology

Interaction of the movement and coat proteins of Maize streak virus: implications for the transport of viral DNA

Huanting Liu,¹† Margaret I. Boulton,¹ Karl J. Oparka² and Jeffrey W. Davies¹

¹ Department of Virus Research, John Innes Centre, Colney, Norwich Research Park, Norwich NR4 7UH, UK
² Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK

We have shown previously that the movement protein (MP) and coat protein (CP) of Maize streak virus (MSV) are both required for systemic infection. Towards understanding the roles of these two proteins in virus movement, each was expressed in E. coli and interactions of the MP with viral DNA or CP were investigated using south-western, gel overlay and immunoprecipitation assays. Unlike the CP, the MP did not bind to viral DNA but it interacted with the CP in vitro and an MP–CP complex was detected in extracts from MSV-infected maize, indicating the potential for an interaction in vivo. Microinjection showed that the MP could prevent the nuclear transport of an MSV CP–DNA complex in maize and tobacco cells. These results are consistent with a model in which the MP diverts a CP–DNA complex from the nucleus (where viral DNA replication takes place) to the cell periphery, and in co-operation with the CP, mediates the cell-to-cell movement of the viral DNA. In this respect, the MSV MP and CP have functional analogy with the BC1 and BV1 proteins, respectively, of the Begomovirus genus of the Geminiviridae.

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© 2000 SGM

This article is now available in the January 2001 print issue of JGV (vol. 82, 35–44). The complete issue of the journal may be seen in electronic form on JGV Online.