Seminar room RB35 (Roslagstullsbacken 35, the SBC house)
Description
Duplication, domain shuffling and de novo creation are some of the mechanisms involved in evolution of new proteins. It is believed that de novo creation is comparatively rare. Anyhow, only about three quarters of the residues in a typical proteome can be matched to a domain in the PfamA and PfamB databases, although this is one of the most sensitive methods available for identifying homology between proteins. Hence, there are parts of sequences and whole proteins where no domains are detected. Is it possible that these sequences are novel, species specific domains?
To answer the question we have estimated the amount of novel material in the proteome of Saccharomyces cerevisiae. Our results show that at least two thirds of the residues are aligned to non-fungal homologs, whereas only a small fraction is species specific. Further, many of the species specific sequences in S. cerevisiae are homologous and associated with transposable elements. Finally, newer sequences are often short, disordered sequences located at the termini. Therefore, we conclude that domain innovation is rare in yeast, however shorter sequences may be created. Other species, for example multicellular eukaryotes, have additional mechanisms for de novo creation, such as exonization of intronic sequences and may contain more novel sequences.
