1z2j
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(New page: 200px<br /> <applet load="1z2j" size="450" color="white" frame="true" align="right" spinBox="true" caption="1z2j" /> '''Solution structure of the HIV-1 frameshift ...)
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Revision as of 12:31, 8 November 2007
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Solution structure of the HIV-1 frameshift inducing element
Overview
Expression of the HIV reverse transcriptase and other essential viral, enzymes requires a -1 translational frameshift. The frameshift event is, induced by two highly conserved RNA elements within the HIV-1 mRNA: a, UUUUUUA heptamer known as the slippery sequence, and a downstream RNA, structure. Here, we report structural and thermodynamic evidence that the, HIV-1 frameshift site RNA forms a stem-loop and lower helix separated by a, three-purine bulge. We have determined the structure of the 45 nucleotide, frameshift site RNA using multidimensional heteronuclear nuclear magnetic, resonance (NMR) methods. The upper helix is highly thermostable (T(m)>90, degrees C), forming 11 Watson-Crick base-pairs capped by a stable ACAA, tetraloop. The eight base-pair lower helix was found to be only moderately, stable (T(m)=47 degrees C). A three-purine bulge separates the highly, stable upper helix from the lower helix. Base stacking in the bulge forms, a wedge, introducing a 60 degrees bend between the helices. Interestingly, this bend is similar to those seen in a number of frameshift inducing, pseudoknots for which structures have been solved. The lower helix must, denature to allow the ribosome access to the slippery site, but likely, functions as a positioning element that enhances frameshift efficiency.
About this Structure
1Z2J is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Solution structure and thermodynamic investigation of the HIV-1 frameshift inducing element., Staple DW, Butcher SE, J Mol Biol. 2005 Jun 24;349(5):1011-23. Epub 2005 Apr 1. PMID:15927637
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