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Citation: Moss WN, Dela-Moss LI, Kierzek E, Kierzek R, Priore SF, et al. (2012) The 3′ Splice Site of Influenza A Segment 7 mRNA Can Exist in Two Conformations: A Pseudoknot and a Hairpin. PLoS ONE 7(6): e38323. doi:10.1371/journal.pone.0038323
Walter N. Moss1#, Lumbini I. Dela-Moss1#, Elzbieta Kierzek2, Ryszard Kierzek2, Salvatore F. Priore1, Douglas H. Turner1*
1 Department of Chemistry, Center for RNA Biology, University of Rochester, Rochester, New York, United States of America, 2 Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Noskowskiego, Poland
Abstract Top
The 3′ splice site of influenza A segment 7 is used to produce mRNA for the M2 ion-channel protein, which is critical to the formation of viable influenza virions. Native gel analysis, enzymatic/chemical structure probing, and oligonucleotide binding studies of a 63 nt fragment, containing the 3′ splice site, key residues of an SF2/ASF splicing factor binding site, and a polypyrimidine tract, provide evidence for an equilibrium between pseudoknot and hairpin structures. This equilibrium is sensitive to multivalent cations, and can be forced towards the pseudoknot by addition of 5 mM cobalt hexammine. In the two conformations, the splice site and other functional elements exist in very different structural environments. In particular, the splice site is sequestered in the middle of a double helix in the pseudoknot conformation, while in the hairpin it resides in a two-by-two nucleotide internal loop. The results suggest that segment 7 mRNA splicing can be controlled by a conformational switch that exposes or hides the splice site.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038323
Walter N. Moss1#, Lumbini I. Dela-Moss1#, Elzbieta Kierzek2, Ryszard Kierzek2, Salvatore F. Priore1, Douglas H. Turner1*
1 Department of Chemistry, Center for RNA Biology, University of Rochester, Rochester, New York, United States of America, 2 Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Noskowskiego, Poland
Abstract Top
The 3′ splice site of influenza A segment 7 is used to produce mRNA for the M2 ion-channel protein, which is critical to the formation of viable influenza virions. Native gel analysis, enzymatic/chemical structure probing, and oligonucleotide binding studies of a 63 nt fragment, containing the 3′ splice site, key residues of an SF2/ASF splicing factor binding site, and a polypyrimidine tract, provide evidence for an equilibrium between pseudoknot and hairpin structures. This equilibrium is sensitive to multivalent cations, and can be forced towards the pseudoknot by addition of 5 mM cobalt hexammine. In the two conformations, the splice site and other functional elements exist in very different structural environments. In particular, the splice site is sequestered in the middle of a double helix in the pseudoknot conformation, while in the hairpin it resides in a two-by-two nucleotide internal loop. The results suggest that segment 7 mRNA splicing can be controlled by a conformational switch that exposes or hides the splice site.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038323