ThiD-TenA: A gene pair fusion in eukaryotes

Computational analysis of the hypothetical open reading frame MJ0236 from Methanococcus jannaschii reveals its membership to a family of bacterial and eukaryotic proteins, predicted to be the HMP-P kinases involved in thiamin biosyntheis (ThiD). The eukaryotic members of this family contain a C-terminal extension similar to a bacterial transcriptional activator (TenA), thus pointing to a fusion event that took place during cellular evolution. The C-terminal domain is absent from M. jannaschii. The significance of this observation is two-fold: first, this is a case where a fusion protein contains two domains with an unusual phylogenetic distribution, and second, the TenA domain is a rare case of a gene family involved in transcription present both in bacteria and eukaryotes.