A new family of aspartyl phosphate phosphatases targeting the sporulation transcription factor Spo0A of Bacillus subtilis

The initiation of the sporulation developmental pathway in Bacillus subtilis is controlled by the phosphorelay, a multicomponent signal transduction system. Multiple positive and negative signals are integrated by the phosphorelay through the opposing activities of histidine protein kinases; and aspartyl phosphate phosphatases. Three members of the Rap family of phosphatases (RapA, RapB and RapE) specifically dephosphorylate the SpoOF similar toP response regulator intermediate, while the SpoOA similar toP transcription factor is specifically dephosphorylated by the SpoOE phosphatase and, as shown here, the newly identified YnzD and Yisl proteins. The products of the YnzD and Yisl genes are highly homologous to SpoOE and define a new family of phosphatases with a distinct signature motif in their amino acid sequence. As negative regulators of the developmental pathway, YnzD and Yisl inhibit spore formation if overexpressed, while a chromosomal deletion of their coding sequences results in increased sporulation frequency. Transcription of the ynzD, yisl and spoOE genes is differentially regulated and generally induced by growth conditions antithetical to sporulation. Negative signals interpreted by aspartyl phosphate phosphatases appear to be a common mechanism in Gram-positive spore-forming microorganisms.