title: Self-assembly Controls Self-cleavage of HHR from ASBVd (-): a Combined SANS and Modeling Study.
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.
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), Dept. of Genome Biology, CEA, CNRS, Université Paris Sud, Gif-sur-Yvette, F-91198, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Leclerc
authors.affiliation: Institut Laue Langevin, Grenoble, F-38042, France.|Institut de Biologie Structurale (IBS), CNRS, Grenoble, F-38044, France.|IBS, CEA, Grenoble, F-38044, France.|IBS, Univ Grenoble Alpes, Grenoble, F-38044, France.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zaccai
authors.affiliation: Institut de Systématique, Evolution, Biodiversité ISyEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, UPMC, Sorbonne Universités, 57 rue Cuvier, CP 50 Paris, F-75005, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Vergne
authors.affiliation: Institut de Systématique, Evolution, Biodiversité ISyEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, UPMC, Sorbonne Universités, 57 rue Cuvier, CP 50 Paris, F-75005, France.|Institute of Physics, Charles University, Faculty of Mathematics and Physics, Prague 2, CZ-121 16, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Řìhovà
authors.affiliation: Institut Laue Langevin, Grenoble, F-38042, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Martel
authors.affiliation: Institut de Systématique, Evolution, Biodiversité ISyEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, UPMC, Sorbonne Universités, 57 rue Cuvier, CP 50 Paris, F-75005, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Maurel
mesh_terms: D009690:Nucleic Acid Conformation; D027421:Persea / Q000821:virology; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics*; D013816:Thermodynamics; D014772:Viroids / Q000737:chemistry / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics*
chemical_list: D012367:RNA, Viral