Poster abstracts
Poster number 49 submitted by Ian Hall
Interactions of structured regulatory RNAs
Ian Hall (Department of Chemistry, University of Michigan), Huaqun Zhang (Biophysics Program, University of Michigan), Amos Nissley (Department of Chemistry, University of Michigan), Sarah Keane (Department of Chemistry & Biophysics Program, University of Michigan)
Abstract:
Listeria monocytogenes is a bacterium causing ~1,600 cases of Listeriosis annually in the USA. The mortality rate of this illness is 20-30% with pregnant women and immune compromised at elevated risk. This pathogen’s virulence is controlled by the PrfA transcription factor which regulates the expression of many virulence genes1. PrfA expression is regulated at the mRNA level by an RNA thermosensor (RNAT) in its 5’ untranslated region. The prfA RNAT is a structured element of the mRNA which sequesters the ribosome binding site (RBS) and start codon at low temperatures suppressing translation of downstream genes. At higher temperatures the RNAT undergoes structural changes, exposing the RBS and promoting translation. Through this mechanism L. monocytogenes uses temperature to trigger virulence2. Additionally, L. monocytogenes harbors a SAM-I riboswitch, sreA, which regulates the expression of a methionine transport system at the transcriptional level. Both sreA and prfA function in cis to control the expression of their respective downstream genes. Interestingly these RNAs also interact in trans to regulate virulence gene expression3. This interaction links nutrient availability and temperature sensing to the virulence of L. monocytogenes4. Additional structure-function work is necessary to understand L. monocytogenes’ virulence regulation. I have initiated a thermodynamic characterization of the interaction by isothermal titration calorimetry. This work will provide quantitative information about the interaction and will guide structural studies by X-ray crystallography, NMR spectroscopy, and small angle X-ray scattering.
References:
1 De Las Heras, A., Cain, R. J., Bielecka, M. K. & Vázquez-Boland, J. A. Regulation of Listeria virulence: PrfA master and commander. Current Opinion in Microbiology 14, 118-127, doi:10.1016/j.mib.2011.01.005 (2011).
2 Loh, E. et al. Temperature triggers immune evasion by Neisseria meningitidis. Nature 502, 237-240, doi:10.1038/nature12616 (2013).
3 Loh, E. et al. A trans-Acting Riboswitch Controls Expression of the Virulence Regulator PrfA in Listeria monocytogenes. Cell 139, 770-779, doi:https://doi.org/10.1016/j.cell.2009.08.046 (2009).
4 Loh, E., Righetti, F., Eichner, H., Twittenhoff, C. & Narberhaus, F. RNA Thermometers in Bacterial Pathogens. 6, doi:doi:10.1128/microbiolspec.RWR-0012-2017 (2018).
Keywords: Thermosensor, Riboswitch, RNA-RNA Interaction