Recombinant Schizosaccharomyces pombe Exosome complex exonuclease dis3 (dis3), partial

Catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and participates in a multitude of cellular RNA processing and degradation events. In the nucleus, the RNA exosome complex is involved in proper maturation of stable RNA species such as rRNA, snRNA and snoRNA, in the elimination of RNA processing by-products and non-coding 'pervasive' transcripts, such as antisense RNA species and cryptic unstable transcripts (CUTs), and of mRNAs with processing defects, thereby limiting or excluding their export to the cytoplasm. In the cytoplasm, the RNA exosome complex is involved in general mRNA turnover and in RNA surveillance pathways, preventing translation of aberrant mRNAs. The catalytic inactive RNA exosome core complex of 9 subunits (Exo-9) is proposed to play a pivotal role in the binding and presentation of RNA for ribonucleolysis, and to serve as a scaffold for the association with catalytic subunits and accessory proteins or complexes. DIS3 has both 3'-5' exonuclease and endonuclease activities. The exonuclease activity of DIS3 is down-regulated upon association with Exo-9 possibly involving a conformational change in the catalytic domain and threading of the RNA substrate through the complex central channel. Structured substrates can be degraded if they have a 3' single-stranded extension sufficiently long (such as 35 nt poly(A)) to span the proposed complex inner RNA-binding path and to reach the exonuclease site provided by dis3. Implicated in mitotic control. Essential for cell division and spore germination. May be involved in regulating protein dephosphorylation during mitosis.