Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Saturday Speaker Abstracts

SINGLE MOLECULE MECHANICS OF PROTEIN FOLDING AND BINDING Matthias Rief ; 1 Technical University of Munich, Physics, Garching, Germany Proteins are amazing molecular machines that can fold into a complex three dimensional structure. Even though powerful structural methods have allowed us taking still photographs of protein structures in atomic detail, the knowledge about the folding pathways and dynamics as well as material properties of those structures is rather limited. Over the past years, our group has developed single mechanical methods to study the dynamics and mechanics of protein structures. In my talk I will discuss how these methods can be used to investigate and control the conformational mechanics of individual proteins. Examples include protein folding as well as protein-protein interactions and enzyme mechanics. ACTIVATION OF A PROTEIN KINASE VIA ASYMMETRIC ALLOSTERIC COUPLING OF STRUCTURALLY CONSERVED SIGNALING MODULES Rodrigo A. Maillard ; 1 Georgetown University, Chemistry, Washington, DC, USA Cyclic nucleotide binding (CNB) domains are universally conserved signaling modules that regulate the activities of diverse protein functions. Yet, the structural and dynamic features that enable the cyclic nucleotide binding signal to allosterically regulate other functional domains remain unknown. We use optical tweezers and molecular dynamics to monitor in real time the pathways of signals transduced by cAMP binding in protein kinase A (PKA). Despite being structurally conserved, we find that the response of the folding energy landscape to cAMP is domain-specific, resulting in unique but mutually coordinated regulatory tasks: one CNB domain initiates cAMP binding and cooperativity, while the other triggers inter-domain interactions that lock the active conformation. Moreover, we identify a new cAMP-responsive switch, whose stability and conformation depends on cAMP occupancy. We show that this dynamic switch is a signaling hub, a previously unidentified role that amplifies the cAMP binding signal during the allosteric activation of PKA.

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