RESPONSE REGULATORS - STRUCTURE, FUNCTION AND EVOLUTION

We have determined the phylogenies of the receiver modules and effector domains of 49 fully sequenced response regulators and their homologues. The phylogenetic tree of the receiver modules revealed three major clusters and several minor clusters, the former of which frequently but not always correlate with the nature of the associated DNA binding domain. The minor clusters of receiver modules were usually but not always associated with other types of effector domains. It is concluded that receiver modules generally diverged from common ancestral protein domains together with the corresponding effector domains, but interdomain splicing, fusion and shuffling has occurred during the evolution of some of these proteins.