Séminaire Alessio Bonucci

09/12/2021 - 11:30 - Jacques Sénez + visio
Alessio BONUCCI, BIP 07

SDSL-EPR spectroscopy: an advantageous tool for the investigations of protein dynamics

An old dogma in structural biology is that folded structures are pivotal for the cellular functions of proteins. Nowadays, these biomolecules are not more considered as static pictures, but as dynamic objects with intrinsic motions. Indeed, a large number of studies demonstrated that the structural flexibility can contribute to several cellular processes such as signaling, transcription regulation and response to stress stimuli. For these reasons, the structural dynamic, which includes the interconversion between multiple conformations, the folding/unfolding mechanisms and the formation of dynamic complexes with other biomolecules or ligands, is a new important aspect to take in account for the characterization of proteins at molecular level.
In this context, Electron Paramagnetic Resonance spectroscopy coupled with Site Directed Spin Labelling techniques (SDSL-EPR) is emerged as powerful method for the investigation of protein conformations and flexibility. Briefly, SDSL-EPR is based on the incorporation of a paramagnetic probe (defined as spin label) onto a selected site of a protein followed by the acquisition EPR signals. Specifically, continuous wave EPR spectra encode information about the local dynamics in a broad time range (ns-s), while pulse EPR experiments provide details about conformational fluctuations by measuring inter-label distances (ranging from 1.5 nm to 8 nm). Here, the basic principles of SDSL reactions and the EPR experiments usually exploited for protein dynamics investigation will be shown. Moreover, different SDSL-EPR applications, as well its integrations with other methods, will be presented in order to explain the type information achievable with this biophysical approach.

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