NOVEL FAMILIES OF PUTATIVE PROTEIN-KINASES IN BACTERIA AND ARCHAEA - EVOLUTION OF THE EUKARYOTIC PROTEIN-KINASE SUPERFAMILY

The central role of serine/threonine and tyrosine protein kinases in s ignal transduction and cellular regulation in eukaryotes is well estab lished and widely documented. Considerably less is known about the pre valence and role of these protein kinases in bacteria and archaea. In order to examine the evolutionary origins of the eukaryotic-type prote in kinase (ePK) superfamily, we conducted an extensive analysis of the proteins encoded by the completely sequenced bacterial and archaeal g enomes. We detected five distinct families of known and predicted puta tive protein kinases with representatives in bacteria and archaea that share a common ancestry with the eukaryotic protein kinases. Four of these protein families have not been identified previously as protein kinases. From the phylogenetic distribution of these families, we infe r the existence of an ancestral protein kinase(s) prior to the diverge nce of eukaryotes, bacteria, and archaea.