One of the most versatile RNA degradation machines in eukaryotes is the 3'‑5' RNA exosome. It consists of nine conserved subunits forming the core complex, which associates with active ribonucleases, RNA binding proteins, helicases and additional co-factors. While yeast and human exosome...

The archaeal exosome is a protein complex with structural similarities to the eukaryotic exosome and bacterial PNPase. Its catalytic core is formed by alternating Rrp41 and Rrp42 polypeptides, arranged in a hexameric ring. A flexible RNA binding cap composed of the evolutionarily conserved...

Long before the RNA degrading exosome was first described in the yeast Saccharomyces cerevisiae, the use of autoantibodies found in the sera of certain autoimmune patients allowed the identification of a complex of polypeptides which later appeared to be the human exosome. Today, the most...

We describe the events surrounding the identification of the exosome complex and the subsequent early development of the field. Like many scientific discoveries, the initial identification and characterization of the exosome was based on a combination of skill, good fortune—and the...

This chapter reviews the present state of knowledge on the activity of enzymes that function with the RNA exosome in the nucleus. In this compartment, the exosome interacts physically and functionally with the exoribonuclease Rrp6 and several cofactors, most prominently Rrp47 and the TRAMP...

A large body of structural work conducted over the past ten years has elucidated mechanistic details related to 3′ to 5′ processing and decay of RNA substrates by the RNA exosome. This chapter will focus on the structural organization of eukaryotic exosomes and their evolutionary cousins...

Heterochromatic silencing is important for repressing gene expression, protecting cells against viral invasion, maintaining DNA integrity and for proper chromosome segregation. Recently, it has become apparent that expression of eukaryotic genomes is far more complex than had previously been...

The eukaryotic exosome complex is built around the backbone of a 9‑subunit ring similar to phosporolytic ribonucleases such as RNase PH and polynucleotide phosphorylase (PNPase). Unlike those enzymes, the ring is devoid of any detectable catalytic activities, with the possible exception of...

Over the last few years, the development of large‑scale technologies has radically modified our conception of genome‑wide transcriptional control by unveiling an unexpected high complexity of the eukaryotic transcriptome. In organisms ranging from yeast to human, a considerable number of...

The exosome consists of a core of ten essential proteins that includes the ribonuclease Rrp44p and is present in both the cytoplasm and nucleus of eukaryotic cells. The cytoplasmic exosome has been extensively characterized in the budding yeast Saccharomyces cerevisiae and some...

The archaeal exosome contains three heterodimeric RNase PH subunits, forming a hexamer with RNase activity; on top sits a trimer of two different SI domain proteins. In animals and yeast, six different, but related subunits form the RNase PH‑like core, but these lack enzyme activity; there...