The nucleocapsid protein of an enveloped plant virus, Tomato spotted wilt virus, facilitates long-distance movement of Tobacco mosaic virus hybrids.
To investigate the potential role(s) of the nucleocapsid (N) protein of Tomato spotted wilt virus (TSWV), the open reading frame for the N protein was expressed from a Tobacco mosaic virus (TMV)-based vector encoding only the TMV replicase proteins. In the absence of other TSWV-encoded proteins, the transiently expressed N protein facilitated long-distance movement of the TMV-based hybrids in transgenic Nicotiana benthamiana [NB-MP(+)] expressing movement protein of TMV, thus providing the functional demonstration of the N protein in long-distance RNA movement. Removal of the N-terminal 39 amino acids (N-NΔ39), the C-terminal 26 amino acids (N-CΔ26) or both of them (N-NΔ39CΔ26) abolished the long-distance movement function, indicating the essential role of both N- and C-terminus. In contrast, alanine substitution of the phenylalanines at positions 242 and 246 (N242/262A), two crucial amino acids for homotypic interaction of the N protein, had little effect, suggesting that the N protein could function in long-distance movement in the form of monomers. In addition, both the wild type N and the alanine mutant N242/262A hardly induced local symptoms in NB-MP(+) plants and TMV-MP transgenic N. tabacum cv. Xanthi. The deletion mutants N-NΔ39, N-CΔ26 and N-NΔ39CΔ26, however, induced apparent symptoms of necrotic ringspots, necrosis or chlorotic spots in all inoculated leaves. On the basis of these findings, the potential role of N during the TSWV infection was discussed. To our knowledge, this is the first report that the N protein of an enveloped plant virus functioned in long-distance movement.
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, 12 South Zhongguancun Street, Beijing 100081, PR China.
Yongqiang
Y
Zhang
Chao
C
Zhang
Weimin
W
Li
D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D019590:Nucleocapsid Proteins / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000821:virology; D030821:Plants, Genetically Modified / Q000821:virology; D017384:Sequence Deletion; D014026:Nicotiana / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000472:pathogenicity*; D017865:Tospovirus / Q000235:genetics / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
D050505:Mutant Proteins; D019590:Nucleocapsid Proteins; D037521:Virulence Factors