Characterization of a Family of Bacterial Response Regulator Aspartyl-Phosphate (RAP) Phosphatases

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Abstract
We have characterized a novel family of response regulator aspartyl-phosphate (RAP) phosphatases found exclusively in gram-positive bacteria. The family consists of 15 members, 12 of which are from Bacillus subtilis. The N-terminal domains proved to be more highly conserved than the C-terminal domains, and a signature sequence for the family was derived from the former domains. Phylogenetic analyses revealed clustering patterns showing that all Bacillus proteins are closely related. Most of the Bacillus RAP phosphatase genes are followed by and are translationally coupled to small nonhomologous phosphatase regulator (phr) genes that encode exported peptides with regulatory functions. Most of the paralogous RAP phosphatases of B. subtilis may serve related functions in signal transduction systems. They appear to have arisen by relatively recent gene duplication events that occurred after the divergence of major groups within the gram-positive bacterial kingdom. We suggest that the N-terminal domains of the RAP phosphatases function in catalysis, whereas the C-terminal domains function in regulation.