Professor Rodrigo Noriega
Physical Chemistry Seminar
Department of Chemistry
University of Utah
Description
Title: Study and Regulation of Biomolecular Interactions at Electrified Interfaces
Abstract: We seek to understand the role of electrostatic interactions in molecular recognition mechanisms that are sensitive to structure but not sequence. An interesting model system for these multifaceted interactions is Loquacious-PD (Loqs-PD), a co-factor protein with two RNA binding motifs that recognize double-stranded RNA (dsRNA) regardless of their terminus structure. Loqs-PD regulates the terminus-dependent binding of the endonuclease enzyme Dicer-2 and is crucial to the efficient processing of sub-optimal dsRNA targets with a 3’ overhang terminus for gene silencing in Drosophila melanogaster.
To identify the effects of electrostatics and local dynamics on the formation and stability of dsRNA:Loqs-PD complexes, we study their binding and dynamics at electrified interfaces with a combination of mid-infrared surface plasmonics, time-resolved ultrafast fluorescence, and in situ electrochemical experiments at the surface of a degenerately doped wide-gap metal oxide. In this way, we distinguish distinct stages in the binding event between an RNA-binding protein and its target and follow dynamic events over multiple time scales. Time-resolved fluorescence measurements show a high affinity interaction that is strongly affected by electric fields, while mid-infrared surface plasmon observations detect a lower affinity interaction with a reduced (but still substantial) sensitivity to electric fields. In both cases, fluctuations are dependent on protein binding and the presence of electric fields.
Multi-stage binding process that arise from non-specific interactions are common between nucleic acids and proteins, and studies that employ complementary observations under controlled perturbations are a powerful tool to interrogate the link between molecular recognition and biochemical function.