title: Molecular basis for RNA polymerization by Qβ replicase.
abstract: Core Qβ replicase comprises the Qβ virus-encoded RNA-dependent RNA polymerase (β-subunit) and the host Escherichia coli translational elongation factors EF-Tu and EF-Ts. The functions of the host proteins in the viral replicase are not clear. Structural analyses of RNA polymerization by core Qβ replicase reveal that at the initiation stage, the 3'-adenine of the template RNA provides a stable platform for de novo initiation. EF-Tu in Qβ replicase forms a template exit channel with the β-subunit. At the elongation stages, the C-terminal region of the β-subunit, assisted by EF-Tu, splits the temporarily double-stranded RNA between the template and nascent RNAs before translocation of the single-stranded template RNA into the exit channel. Therefore, EF-Tu in Qβ replicase modulates RNA elongation processes in a distinct manner from its established function in protein synthesis.
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan.
authors.forename: Daijiro
authors.initials: D
authors.lastname: Takeshita
authors.forename: Kozo
authors.initials: K
authors.lastname: Tomita
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000821:virology*; D010444:Peptide Elongation Factor Tu / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000378:metabolism; D058105:Polymerization; D055503:Protein Multimerization; D011777:Q beta Replicase / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*
chemical_list: D010445:Peptide Elongation Factors; D012367:RNA, Viral; C023512:elongation factor Ts; D011777:Q beta Replicase; D010444:Peptide Elongation Factor Tu