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Publication Abstract from PubMed

The genomic RNA of Qbeta virus is replicated by Qbeta replicase, a template-dependent RNA polymerase complex. Qbeta replicase has an intrinsic template-independent RNA 3'-adenylation activity, which is required for efficient viral RNA amplification in the host cells. However, the mechanism of the template-independent 3'-adenylation of RNAs by Qbeta replicase has remained elusive. We determined the structure of a complex that includes Qbeta replicase, a template RNA, a growing RNA complementary to the template RNA, and ATP. The structure represents the terminal stage of RNA polymerization and reveals that the shape and size of the nucleotide-binding pocket becomes available for ATP accommodation after the 3'-penultimate template-dependent C-addition. The stacking interaction between the ATP and the neighboring Watson-Crick base pair, between the 5'-G in the template and the 3'-C in the growing RNA, contributes to the nucleotide specificity. Thus, the template for the template-independent 3'-adenylation by Qbeta replicase is the RNA and protein ribonucleoprotein complex.

Mechanism for template-independent terminal adenylation activity of Qbeta replicase.,Takeshita D, Yamashita S, Tomita K Structure. 2012 Oct 10;20(10):1661-9. doi: 10.1016/j.str.2012.07.004. Epub 2012, Aug 9. PMID:22884418^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.