Antibody inhibition of the transcriptase activity of the rotavirus DLP: a structural view

E Thouvenin, G Schoehn, F Rey, I Petitpas… - Journal of molecular …, 2001 - Elsevier
E Thouvenin, G Schoehn, F Rey, I Petitpas, M Mathieu, MC Vaney, J Cohen, E Kohli…
Journal of molecular biology, 2001Elsevier
On entering the host cell the rotavirus virion loses its outer shell to become a double-layered
particle (DLP). The DLP then transcribes the 11 segments of its dsRNA genome using its
own transcriptase complex, and the mature mRNA emerges along the 5-fold axis. In order to
better understand the transcription mechanism and the role of VP6 in transcription we have
studied three monoclonal antibodies against VP6: RV-238 which inhibits the transcriptase
activity of the DLP; and RV-133 and RV-138 which have no effect on transcription. The …
On entering the host cell the rotavirus virion loses its outer shell to become a double-layered particle (DLP). The DLP then transcribes the 11 segments of its dsRNA genome using its own transcriptase complex, and the mature mRNA emerges along the 5-fold axis. In order to better understand the transcription mechanism and the role of VP6 in transcription we have studied three monoclonal antibodies against VP6: RV-238 which inhibits the transcriptase activity of the DLP; and RV-133 and RV-138 which have no effect on transcription. The structures obtained by cryo-electron microscopy of the DLP/Fab complexes and by X-ray crystallography of the VP6 trimer and the VP6/Fab-238 complex have been combined to give pseudo-atomic structures. Steric hindrance between the Fabs results in limited Fab occupancy. In particular, there are on average only three of a possible five Fabs-238 which point towards the 5-fold axis. Thus, Fabs-238 are not in a position to block the exiting mRNA, nor is there any visible conformational change in VP6 on antibody binding at a resolution of 23 Å. However, the epitope of the inhibiting antibody involves two VP6 monomers, whereas, those of the non-inhibiting antibodies have an epitope on only one VP6. Thus, the inhibition of transcription may be a result of inhibition of a possible change in the VP6 conformation associated with the transcription of mRNA.
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