Abstract
In Rhodobacter sphaeroides f. sp. denitrificans IL106, the DmsS/DmsR two-component signal transduction system regulates the expression of dmsCBA operon encoding DMSO(dimethylsulfoxide)respiration system. DmsS has no putative membrane-spanning hydrophobic amino acid regions, although other sensor histidine kinases generally contain transmembrane regions.
To analyze membrane-binding region of DmsS dmsS-lacZ fusion genes were constructed. Each strain had the LacZ activity, suggesting that each LacZ protein was located in the cytoplasm. The LacZ fusion proteins were recovered in the cytoplasmic and membrane fractions, suggesting that the fusion proteins binded loosely to the membrane from the cytoplasmic side. Although DMSO induces the expression of DmsA protein under anaerobic conditions, no change of dmsS promoter activity was observed by DMSO, suggesting that DMSO is not a transcription signal of dmsS.
