Poster abstracts

Poster number 5 submitted by Sumirtha Balaratnam

Effect of divalent metal ions on the stability of RNA G-quadruplex

Sumirtha Balaratnam (Department of Chemistry and Biochemistry), Soumitra Basu (Department of Chemistry and Biochemistry)

Abstract:
DNA and RNA sequences rich in guanosines (G) can form a four-stranded secondary structure known as a G-quadruplex (GQ), which are found in mammals, fungi and plants and have been extensively studied. They are known to play a role in regulation of gene expression at the transcription and translation level. Both DNA and RNA GQs require monovalent cation (K+) for stabilization of the structures. Effect of divalent metal ions on DNA GQ stability has been studied; however, their effect on RNA GQs remains unknown. We investigated the role of alkaline earth metal cations and a set of divalent transition metal ions on an RNA GQ found within the 5'-untranslated region of matrix metalloproteinase (MT3-MMP) mRNA (M3Q). Our results based upon circular dichroism and RNAse T1 footprinting data reveal that the RNA GQ is destabilized in the presence of the divalent metal cations tested. Transition metal cations are destabilizing the RNA GQ more than alkaline earth cations. However these effects are reversible upon increasing the monovalent cation (K+). We are systematically investigating the characteristic features of the divalent metal ions that are responsible for the destabilization. The results will be valuable in understanding the properties of metal ions that are important to binding and stability of RNA GQs.

References:
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2. Mark .J. Morris and Soumitra Basu. (2009) An unusually stable G-quadruplex within the 5' UTR of the MT3 matrix metalloproteinase mRNA represses translation in eukaryotic cells. Biochemistry ACS, 48, 5313-5319.
3. Kathryn Phillips, Zbyszek Dauter, Alastair I. H. Murchie,David M. J. Lilley and Ben Luisi.(1997) The Crystal Structure of a Parallel-stranded Guanine Tetraplex at 0.95AÊ Resolution, J Mol. Biol, 273,171-182.
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Keywords: RNA G- quadruplex, divalent metal ions, destabilization