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bioRxiv · 10.1101/045054

Self-assembly Controls Self-cleavage of HHR from ASBVd(-): a Combined SANS and Modeling Study.

Fabrice Leclerc·Giuseppe Zaccai·Jacques Vergne·Martina Rihova·Anne Martel·Marie-Christine Maurel
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Abstract

In the Avocado Sunblotch Viroid (ASBVd: 249-nt) from the Avsunviroidae family, a symmetric rolling-circle replication operates through an autocatalytic mechanism mediated by hammerhead ribozymes (HHR) embedded in both polarity strands. The concatenated multimeric ASBVd (+) and ASBVd (-) RNAs thus generated are processed by cleavage to unit-length where ASBVd (-) self-cleaves with more efficiency. Absolute scale small angle neutron scattering (SANS) revealed a temperature-dependent dimer association in both ASBVd (-) and its derived 79-nt HHR (-). A joint thermodynamic analysis of SANS and catalytic data indicates the rate-determining step corresponds to the dimer/monomer transition. 2D and 3D models of monomeric and dimeric HHR (-) suggest that the inter-molecular contacts stabilizing the dimer (between HI and HII domains) compete with the intra-molecular ones stabilizing the active conformation of the full-length HHR required for an efficient self-cleavage. Similar competing intra- and inter-molecular contacts are proposed in ASBVd (-) though with a remoter region from an extension of the HI domain.

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Fabrice Leclerc, Giuseppe Zaccai, Jacques Vergne, Martina Rihova, Anne Martel, Marie-Christine Maurel. 2016-03-23. Self-assembly Controls Self-cleavage of HHR from ASBVd(-): a Combined SANS and Modeling Study.. https://doi.org/10.1101/045054

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