4q7j
Complex structure of viral RNA polymerase
Structural highlights
FunctionEFTS_ECOLI Associates with the EF-Tu.GDP complex and induces the exchange of GDP to GTP. It remains bound to the aminoacyl-tRNA.EF-Tu.GTP complex up to the GTP hydrolysis stage on the ribosome.[HAMAP-Rule:MF_00050] Publication Abstract from PubMedRibosomal protein S1, consisting of six contiguous OB-folds, is the largest ribosomal protein and is essential for translation initiation in Escherichia coli. S1 is also one of the three essential host-derived subunits of Qbeta replicase, together with EF-Tu and EF-Ts, for Qbeta RNA replication in E. coli. We analyzed the crystal structure of Qbeta replicase, consisting of the virus-encoded RNA-dependent RNA polymerase (beta-subunit), EF-Tu, EF-Ts and the N-terminal half of S1, which is capable of initiating Qbeta RNA replication. Structural and biochemical studies revealed that the two N-terminal OB-folds of S1 anchor S1 onto the beta-subunit, and the third OB-fold is mobile and protrudes beyond the surface of the beta-subunit. The third OB-fold mainly interacts with a specific RNA fragment derived from the internal region of Qbeta RNA, and its RNA-binding ability is required for replication initiation of Qbeta RNA. Thus, the third mobile OB-fold of S1, which is spatially anchored near the surface of the beta-subunit, primarily recruits the Qbeta RNA toward the beta-subunit, leading to the specific and efficient replication initiation of Qbeta RNA, and S1 functions as a replication initiation factor, beyond its established function in protein synthesis. Molecular insights into replication initiation by Qbeta replicase using ribosomal protein S1.,Takeshita D, Yamashita S, Tomita K Nucleic Acids Res. 2014 Aug 13. pii: gku745. PMID:25122749[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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