Exosome Complex

Abstract

A living cell consists in a dynamic equilibrium of many opposing processes. Steady‐state levels of all ribonucleic acid (RNA) and protein molecules result from a specific balance between constant production and ongoing decay. RNA degradation is thus of paramount importance for the cell's wellbeing. A major player in this process is the exosome complex. It is a multisubunit entity endowed with ribonuclease activities. It is highly conserved in evolution, found in all Eukaryota and most Archaea ; Eubacteria lack the exosome but they do have a very similar enzyme. The eukaryotic exosome has endo‐ and exoribonuclease activity and it engages a plethora of substrates in numerous pathways of RNA decay, RNA processing and RNA surveillance. Substrate specificity is conferred by a wide range of cofactors, some of them multisubunit complexes with interaction networks of their own. Key Concepts: The exosome core is a conserved protein complex. Exosomes of Archaea and Eukaryota have different enzymatic activities. Catalytic activity in eukaryotic exosomes comes from noncore subunits. Catalytic subunits are organised differently in yeast, plants and mammals. The exosome participates in RNA decay, processing and surveillance. Many cofactors are responsible for recruiting substrates to the exosome.