Involvement of ResE phosphatase activity in down-regulation of ResD-controlled genes in Bacillus subtilis during aerobic growth

The ResD-ResE signal transduction system is required for aerobic and anaerobic respiration in Bacillus subtilis. The histidine sensor kinase ResE, by functioning as a kinase and a phosphatase for the cognate response regulator ResD, controls the level of phosphorylated ResD. A high level of phosphorylated ResD is postulated to cause a dramatic increase in transcription of ResDE-controlled genes under anaerobic conditions. A mutant ResE, which retains autophosphorylation and ResD phosphorylation activities but is defective in ResD dephosphorylation, allowed partially derepressed aerobic expression of the ResDE-controlled genes. The result indicates that phosphatase activity of ResE is regulated by oxygen availability and anaerobic induction of the ResDE regulon is partly due to a reduction of the ResE phosphatase activity during anaerobiosis. That elimination of phosphatase activity does not result in complete aerobic derepression suggests that the ResE kinase activity is also subject to control in response to oxygen limitation.