Single-Molecule FRET Reveals a Corkscrew RNA Structure for the Polymerase-Bound Influenza Virus Promoter
Single-molecule FRET reveals a corkscrew RNA PNAS PLUS structure for the polymerase-bound influenza virus promoter Alexandra I. Tomescua,1, Nicole C. Robba,1, Narin Hengrungb,c, Ervin Fodorb,2, and Achillefs N. Kapanidisa,2 aBiological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom; bSir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom; and cDivision of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom Edited by Robert A. Lamb, Northwestern University, Evanston, IL, and approved July 8, 2014 (received for review April 1, 2014) The influenza virus is a major human and animal pathogen re- development of specific antiviral agents, such as decoy RNAs sponsible for seasonal epidemics and occasional pandemics. The (10). Despite this, little structural information is available re- genome of the influenza A virus comprises eight segments of single- garding the mechanisms of RNA promoter recognition and stranded, negative-sense RNA with highly conserved 5′ and 3′ ter- binding by the influenza virus RNAP. mini. These termini interact to form a double-stranded promoter During the influenza virus life cycle, the viral RNAP tran- structure that is recognized and bound by the viral RNA-dependent scribes the vRNA genome into capped and polyadenylated RNA polymerase (RNAP); however, no 3D structural information for mRNAs using short primers containing a 5′ 7-methyl-guanosine the influenza polymerase-bound promoter exists. Functional studies cap structure derived from host cell pre-mRNAs. The vRNA have led to the proposal of several 2D models for the secondary segments are also replicated by the RNAP via cRNA inter- structure of the bound promoter, including a corkscrew model in mediates, which in turn are used as templates to make more ′ ′ which the 5 and 3 termini form short hairpins.
[Show full text]