Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 24: Posters - Single Molecule Biophysics
BP 24.3: Poster
Montag, 7. März 2016, 17:30–19:30, Poster C
Complex Folding Kinetics of the SAM-I Riboswitch Expression Platform Revealed by Single-molecule FRET and HMM Analysis — •Christoph Manz1, Andrei Yu Kobitski1, Bettina Keller2, Ayan Samanta3, Andres Jäschke3, and Gerd Ulrich Nienhaus1,4 — 1Institute of Applied Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany — 2Institute of Chemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany — 3Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany and Molecular Biotechnology, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany — 4Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA
Isolated aptameric domains of riboswitches have been studied intensively, whereas detailed knowledge on interactions between the aptamer and the expression platform of entire riboswitches is still lacking. We have studied the structure and dynamics of a complete S-adenosylmethionine-I riboswitch (SAM-I RS) at different Mg2+ and ligand concentrations by using single-molecule Förster resonance energy transfer (smFRET). To observe conformational changes in real time, we performed Mg2+ and SAM titration experiments on freely diffusing and on surface-immobilized SAM-I RS, using various FRET-labeled constructs. Data were analyzed with a newly developed hidden Markov model and an optimization procedure for photon-based smFRET data, yielding a detailed folding pathway for the SAM-I RS.