The cognate coat protein is required for cell-to-cell movement of a chimeric brome mosaic virus mediated by the cucumber mosaic virus movement protein.
Cucumber mosaic cucumovirus (CMV) and brome mosaic bromovirus (BMV) have many similarities, including the three-dimensional structure of virions, genome organizations, and requirement of the coat protein (CP) for cell-to-cell movement. We have shown that a chimeric BMV with the CMV 3a movement protein (MP) gene instead of its own cannot move from cell to cell in Chenopodium quinoa, a common permissive host for both BMV and CMV. Another chimeric BMV was constructed by replacing both MP and CP genes of BMV with those of CMV (MP/CP-chimera) and tested for its infectivity in C. quinoa, to determine whether the CMV CP has some functions required for the CMV MP-mediated cell-to-cell movement and to exhibit functional difference between CPs of BMV and CMV. Cell-to-cell movement of the MP/CP-chimera occurred, and small local lesions were induced on the inoculated leaves. A frameshift mutation introduced in the CMV CP gene of the MP/CP-chimera resulted in a lack of cell-to-cell movement of the chimeric virus. These results indicate that the viral movement mediated by the CMV MP requires its cognate CP. Deletion of the amino-terminal region in CMV CP, which is not obligatory for CMV movement, also abolished cell-to-cell movement of the MP/CP-chimera. This may suggest some differences in cell-to-cell movement of the MP/CP-chimera and CMV. On the other hand, the sole replacement of BMV CP gene with that of CMV abolished viral cell-to-cell movement, suggesting a possibility that the viral movement mediated by the BMV MP may also require its cognate CP. Functional compatibility between MP and CP in viral cell-to-cell movement is discussed.
Nagano
H
H
Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan. nagano@kais.kyoto-u.ac.jp
Mise
K
K
Okuno
T
T
Furusawa
I
I
D000595:Amino Acid Sequence; D017795:Bromovirus / Q000235:genetics / Q000502:physiology*; D002213:Capsid / Q000235:genetics / Q000378:metabolism*; D017799:Cucumovirus / Q000235:genetics; D005814:Genes, Viral; D008969:Molecular Sequence Data; D016296:Mutagenesis; D053830:Plant Viral Movement Proteins; D011523:Protoplasts / Q000821:virology; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D053830:Plant Viral Movement Proteins; D014764:Viral Proteins