Crystal structure of 3WJ core revealing divalent ion-promoted thermostability and assembly of the Phi29 hexameric motor pRNA

Crystal structure of bacteriophage phi29 pRNA-3WJ motif was solved at 3.05 Å, revealing two divalent metal ions that coordinate 4 nt of the RNA fragments. Subsequent modeling of the phi29 connector/pRNA complex suggests that the pRNA of the phi29 DNA packaging motor exists as a hexameric complex serving as a sheath over the connector. The study helps to elucidate the structural basis for the usual stability of the pRNA-3WJ, as well as gives insights in designing therapeutics RNA nanoparticles using pRNA-3WJ as scaffold.