Deciphering co-translational protein folding, assembly and quality control pathways, in health and disease

Descripción del proyecto

La importancia de las proteínas bien plegadas

Aún no se conocen bien los mecanismos que aseguran el correcto plegado y ensamblaje de las proteínas en el citoplasma abarrotado. El creciente número de enfermedades por el mal plegado destaca la importancia que tiene el desafío del plegado. El ribosoma se plantea como un centro en la intersección crítica entre la síntesis y el plegado. Recientemente se descubrió que incluso el paso final del plegado, el ensamblaje en complejos, está coordinado con la traducción. Los miembros del proyecto RiboFriend, financiado con fondos europeos, desarrollaron un método de elaboración de perfiles de ribosomas para captar eventos cotraduccionales «in vivo». Sin embargo, los mecanismos que regulan las vías de ensamblaje cotraduccionales siguen sin estar claros. El equipo del proyecto explicará los mecanismos de degradación y plegado de las proteínas cotraduccionales en la salud y la enfermedad, lo que mejorará la comprensión de las enfermedades conformacionales y el proceso de envejecimiento, y abrirá nuevas vías para tratamientos.

Objetivo

The majority of cellular proteins do not function alone; rather acting together to achieve concerted functions. Despite the prevalence of protein complexes, little is known of the mechanisms that ensure their correct folding and assembly in the crowded cytoplasm. The importance of the folding challenge is underscored by the growing number of misfolding diseases, often characterized by aggregation of lonely, unassembled protein-subunits.
At the critical intersection of synthesis and folding, the ribosome is emerging as a hub, guiding the polypeptide-chain interactions with targeting factors, modifying enzymes and folding chaperones. We have recently discovered that even the final step of folding, the assembly into complexes, is coordinated with translation. To capture co-translational events, in vivo, we developed a ribosome profiling approach. This approach revealed that emerging polypeptide-chains are constantly engaged by their partner subunits, protecting them from misfolding (Shiber et al., Nature 2018). However the mechanisms regulating co-translational assembly pathways remain largely obscure. In this proposal, we aim to elucidate co-translational protein folding and degradation mechanisms, in health and disease.
We will: (i) Identify and characterize novel co-translational degradation pathways, by targeting ribosomes synthesizing misfolding-prone subunits. (ii) Elucidate the conformational, energetic and kinetic parameters directing folding and assembly, at the atomic level, by molecular dynamics (iii) Develop RiboFriend a single-molecule in vivo approach to elucidate the interplay of chaperones, degradation and assembly factors, during synthesis. Our collective preliminary results strongly support the feasibility of this proposal. The ability to capture co-translational folding and misfolding pathways, in single-molecule resolution can revolutionize our understanding of conformational diseases and the aging process, opening new horizons for therapy.