SPECIAL TIME AND LOCATION - RNA conformations and dynamics in splicing complexes as studied using multidimensional and single-molecule spectroscopy.

Date: 
Monday, January 12, 2015 - 2:00pm to Tuesday, January 13, 2015 - 10:00am
Speaker: 
Julia Widom
Speaker's Institution: 
University of Michigan

Research Interests

RNA conformations and dynamics in splicing complexes as studied using multidimensional and single-molecule spectroscopy.

Seminars

Monday, January 12, 2pm, 331 Klamath Hall: Research Seminar 

Tuesday, January 13, 9am, 217 LISB: Future Research Workshop

Title and Abstract

"Structure and Dynamics of Nucleic Acids by Nonlinear Spectroscopy and Single-Molecule Microscopy"

Nucleic acids play central roles in many aspects of biology, acting as genetic material, catalysts, regulatory molecules and more. Advancements in optical spectroscopy and microscopy have greatly expanded the types of information that are accessible when studying functional nucleic acids and protein-nucleic acid complexes, providing great insight into their biological function. In my seminar, I will first present two-dimensional fluorescence spectroscopy as a powerful technique for probing the conformations of systems exhibiting electronic coupling. This approach has been used to solve the solution conformation of a dinucleotide of the fluorescent adenine analogue 2-aminopurine, and is now being extended to more complex DNA systems. Second, I will present single-molecule Förster resonance energy transfer (smFRET) studies of protein-nucleic acid complexes involved in splicing and transcription. I will present previous and ongoing work in which smFRET was used to investigate the roles of RNA helicases in remodeling the protein and RNA architecture of the spliceosome. I will discuss the helicase Prp22 from S. cerevisiae, focusing on unwinding studies using model substrates. Finally, I will present smFRET studies on the preQ1 riboswitch from B. subtilis, which functions by regulating transcription termination in response to its ligand, the guanine analogue preQ1. I investigated the dynamics of the riboswitch in isolation and in active transcription complexes, with the goal of understanding the interplay between ligand sensing by the riboswitch and transcription by RNA polymerase. Planned future work on this system includes determining the role of co-transcriptional folding in riboswitch function. Through studies such as these, processes of key biological and medicinal importance like transcription and splicing can be understood at a molecular level. 

Select Publications

Widom, J. R.; Perdomo?Ortiz, A.; Lee, W.; Rappoport, D.; Molinski, T. F.; Aspuru?Guzik, A.; Marcus, A. H. “Temperature?Dependent Conformations of a Membrane Supported ‘Zinc Porphyrin Tweezer’ by 2D Fluorescence Spectroscopy,” J. Phys. Chem. A. 2013, 117, 6171 – 6184. 

Widom, J. R.; Rappoport, D.; Perdomo?Ortiz, A.; Thomsen, H.; Johnson, N. P.; von Hippel, P. H.; Aspuru?Guzik, A.; Marcus, A. H. “Electonic Transition Moments of 6?Methyl Isoxanthopterin – a Fluorescent Analogue of the Nucleic Acid Base Guanine.” Nucleic Acids Res., 2013, 41, 995?1004. 

Widom, J. R.; Johnson, N. P.; von Hippel, P. H.; Marcus, A. H. “Solution Conformation of 2?Aminopurine (2?AP) Dinucleotide by Ultraviolet 2D Fluorescence Spectroscopy (UV? 2D FS),” New J. Phys., 2013, 15, 025028?1?16.