The exosome is a multisubunit exonuclease complex that degrades many types of RNAs, in many different contexts, in a 3′ to 5′ manner. The catalytic component of the exosome is the Dis3 subunit. Dis3 contains a PIN domain, which is sometimes associated with nuclease activity. This work shows that the Dis3 PIN domain also possesses endonuclease activity (that is, it can cleave RNA internally, rather than from an end). Mutations in either this domain or in the exonuclease domain exhibit a growth phenotype, suggesting that both activities are physiologically important.
- Alice Lebreton
- Rafal Tomecki
- Bertrand Séraphin