Poster abstracts
Poster number 74 submitted by Weicheng Li
Validating and Optimizing Mechanistic Model of Cooperative Ligand Binding to the Oligomeric Trp- and RNA-binding protein TRAP
Weicheng Li (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH43210), Elihu C. Ihms (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH43210), Ian R. Kleckner (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH43210), Melody L. Holmquist (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH43210), Paul Gollnick (Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY14260), Mark P. Foster (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH43210)
Abstract:
Biological networks are frequently regulated via the cooperative binding of multiple ligands. Cooperativity serves to fine tune regulatory circuits by amplifying or dampening a response to a cellular signal. Cooperativity can be synergistic (positive), or interfering (negative), depending on whether the affinity of subsequent ligands binding is increased or decreased by the effect of previous binding event. Despite its ubiquity and importance, our understanding of mechanisms of cooperativity remains limited. TRAP (trp RNA-binding Attenuation Protein) is a homo-undecamer whose RNA binding activity is regulated by binding of L-tryptophan (Trp) to its eleven identical binding sites. The Trp binding events are thought to stabilize the RNA-binding state of TRAP and favor RNA binding. Trp binding events show cooperativity in Bsu TRAP, Bst TRAP, and Bst TRAP A28I via isothermal titration calorimetry (ITC) experiments. By fitting temperature-dependent ITC data using a nearest-neighbor (NN) statistical thermodynamic model, Trp binding to Bst TRAP A28I we quantify the microscopic contributions of Trp binding to the affinity at neighboring sites. The NN model assumes that binding of Trp to one of its 11 sites will energetically affect binding at the adjacent sites (nearest-neighbor) in TRAP ring. This model is able to reproduce thermodgrams of Trp-binding to Bst TRAP A28I over a range of temperatures. We continue to apply this NN model to test its ability to predict Trp and RNA binding to wild-type Bst TRAP and Bsu TRAP.
References:
1.Ihms, E. C., Kleckner, I. R., Gollnick, P., & Foster, M. P. (2017). Mechanistic Models Fit to Variable Temperature Calorimetric Data Provide Insights into Cooperativity. Biophysical journal, 112(7), 1328-1338.
Keywords: Cooperativity, ITC, Statistical thermodynamic model