Archaeal PROTEasome Interaction Network (PROTE-IN): linking proteasome function with RNA quality control. – PROTE-IN

The accumulation of stalled and defective ribosomes is induced by stress and is associated with ageing and with many diseases. Understanding how cells get rid of defective ribosomes represent a major challenge in fundamental biology and biomedicine. The PROTE-IN project addresses this pivotal question using a prokaryotic archaeal model possessing eukaryotic-like protein and RNA quality control systems. Our work indicates for the first time the existence of a targeting system addressing the proteasome to the ribosome to ensure the destruction of the defective translational machinery. Moreover, our observations suggest that, in this process, the proteasome and the RNA degradation machinery works synergistically. In hyperthermophilic archaea, we have identified an RNA-binding adaptive protein, dubbed Z3, that interacts with proteasome. We propose that Z3 acts as a critical nexus in coordinating the degradation activity of the proteasome with the RNA processing activity of the exosome and the tRNA modification activity of the KEOPS complex. To test this hypothesis the first objective is to specify the physiological role(s) of the Z3 factor and its partners (Task1). We also want to identify and characterize the key players linking the proteasome-ribosome-exosome interaction network (Task2). Finally, we want determine the structural organization and the mode of action of the supramolecular protein-RNA quality control edifice (Task3). This proposal is a collaboration between four recognize teams with unique complementary expertise in protein degradation and RNA processing in Archaea as well as specific skills in the structural biology and microbiology of hyperthermophilic systems. The proposal builds upon solid preliminary data and pilot experiments assessing that there are no major technical issues for the proposed tasks. The PROTE-IN work program will combine advanced genetics and interactomics tools as well as integrated structural biology methods on reconstructed and native archaeal complexes (SAXS-SANS/X-ray crystallography and CryoEM). The project should establish a new concept for a better understanding of the adaptation of living organisms to extreme environments and will shed light on RNA-protein complexes disassembling, a fundamental yet poorly understood mechanism in all cell types.