Syracuse

Observing protein degradation by the PAN-20S proteasome by time-resolved neutron scattering

Archive ouverte

Mahieu, Emilie | Covès, Jacques | Krüger, Georg | Martel, Anne | Moulin, Martine | Carl, Nico | Härtlein, Michael | Carlomagno, Teresa | Franzetti, Bruno | Gabel, Frank

Edité par CCSD ; Biophysical Society -

International audience. The proteasome is a key player of regulated protein degradation in all kingdoms of life. Although recent atomic structures have provided snapshots on a number of conformations, data on substrate states and populations during the active degradation process in solution remain scarce. Here, we use time-resolved small-angle neutron scattering of a deuterium-labeled GFPssrA substrate and an unlabeled archaeal PAN-20S system to obtain direct structural information on substrate states during ATP-driven unfolding and subsequent proteolysis in solution. We find that native GFPssrA structures are degraded in a biexponential process, which correlates strongly with ATP hydrolysis, the loss of fluorescence, and the buildup of small oligopeptide products. Our solution structural data support a model in which the substrate is directly translocated from PAN into the 20S proteolytic chamber, after a first, to our knowledge, successful unfolding process that represents a point of no return and thus prevents dissociation of the complex and the release of harmful, aggregation-prone products.

• Description
• Sujet/Public
• Outil
• Outil d'anticipation
• Mémoire et thèse
• Gestion