A large kinome in a large cell: Stentor coeruleus possesses highly expanded kinase families and novel domain architectures

Background Stentor coeruleus is a large ciliated protist, about 1mm in length, with the extraordinary ability to fully regenerate each fragment after being cut into pieces, perfectly restoring cell polarity and morphology. Single-cell regeneration in Stentor remains one of the greatest long-standing mysteries of biology, but the recently published Stentor genome now enables studies on this organism at the molecular and genetic levels. Here we characterize the complete complement of kinases, or kinome, of Stentor, in order to begin to understand the signaling capacities that underlie Stentor ’s unique biology. Results The genome of S. coeruleus contains over 2000 kinases, representing 6% of the predicted proteome. Classification of the kinase genes reveals large expansions in several kinase families, particularly in the CDPKs, the DYRKs, and in several mitotic kinase families including the PLKs, NEKs, and Auroras. The large expansion of the CDPK and DYRK kinase families is an unusual feature of the Stentor kinome compared to other ciliates with sequenced genomes. The DYRK family in Stentor, notably, contains only a single pseudokinase which may suggest an important role in Stentor growth and survival, while the smaller PEK family contains a novel pseudokinase subfamily. The Stentor kinome also has examples of new domain architectures that have not been previously observed in other organisms. Conclusion Our analysis provides the first gene-level view into the signaling capabilities of Stentor and will lay the foundation for unraveling how this organism can coordinate processes as complex as regeneration throughout a giant cell.