Structural basis of rotavirus RNA chaperone displacement and RNA annealing

Bravo, J. P. K.; Bartnik, K.; Venditti, L.; Gail, E. H.; Davidovich, C.; Lamb, D. C.; Tuma, R.; Calabrese, A. N.; Borodavka, A.

doi:10.1101/2020.10.26.354233

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bioRxiv · 10.1101/2020.10.26.354233

Structural basis of rotavirus RNA chaperone displacement and RNA annealing

Bravo, J. P. K.·Bartnik, K.·Venditti, L.·Gail, E. H.·Davidovich, C.·Lamb, D. C.·Tuma, R.·Calabrese, A. N.·Borodavka, A.

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Abstract

Rotavirus genomes are distributed between eleven distinct RNA molecules, all of which must be selectively co-packaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 auto-regulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, whilst accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch poised towards RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation whilst promoting inter-molecular RNA interactions may be a widespread strategy of RNA chaperone recycling.

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Bravo, J. P. K., Bartnik, K., Venditti, L., Gail, E. H., Davidovich, C., Lamb, D. C., Tuma, R., Calabrese, A. N., Borodavka, A.. 2020-10-26. Structural basis of rotavirus RNA chaperone displacement and RNA annealing. https://doi.org/10.1101/2020.10.26.354233

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