A recent article in RNA – “The exozyme model: A continuum of functionally distinct complexes” – provides at once a timely review of exosome structure and function, and an interesting hypothesis that attempts to explain some interesting features of the exosome as it is found in different eukaryotes.
Recall that the exosome is the term for a (THE) RNA degrading machine in eukaryotes, and that it is analogous in many ways to the degradosome in bacteria. Over the years, various and sundry exosome subunits have been implicated by genetics or biochemistry in numerous RNA processing and degrading events or systems. However, there are differences, in terms of subunit composition and activity, between different organisms. Because of these differences (that I won’t list here – Kiss and Andrulis do an excellent job that would take thousands of words to summarize), the authors of the cited review propose that the “exosome” is better thought of as a collection of “exozymes”, all of which share some subset of the subunits that collectively are usually associated with the conceptual exosome. In the authors’ own words: Read the rest of this entry »