RNA helicase domain of tobamovirus replicase executes cell-to-cell movement possibly through collaboration with its nonconserved region.
UR-hel, a chimeric virus obtained by replacement of the RNA helicase domain of tobacco mosaic virus (TMV)-U1 replicase with that from the TMV-R strain, could replicate similarly to TMV-U1 in protoplasts but could not move from cell to cell (K. Hirashima and Y. Watanabe, J. Virol. 75:8831-8836, 2001). It was suggested that TMV recruited both the movement protein (MP) and replicase for cell-to-cell movement by unknown mechanisms. Here, we found that a recombinant, UR-hel/V, in which the nonconserved region was derived from TMV-R in addition to the RNA helicase domain of replicase, could move from cell to cell. We also analyzed revertants isolated from UR-hel, which recovered cell-to-cell movement by their own abilities. We found amino acid substitutions responsible for phenotypic reversion only in the nonconserved region and/or RNA helicase domain but never in MP. Together, these data show that both the nonconserved region and the RNA helicase domain of replicase are involved in cell-to-cell movement. The RNA helicase domain of tobamovirus replicase possibly does not interact directly with MP but interacts with its nonconserved region to execute cell-to-cell movement.
Hirashima
Kyotaro
K
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan.
Watanabe
Yuichiro
Y
D053830:Plant Viral Movement Proteins; D020365:RNA Helicases / Q000737:chemistry / Q000502:physiology*; D017898:Tobamovirus / Q000201:enzymology / Q000502:physiology*; D014764:Viral Proteins / Q000502:physiology
D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D020365:RNA Helicases