Rapid dephosphorylation of the TorR response regulator by the TorS unorthodox sensor in Escherichia coli.
Induction of the torCAD operon, encoding the trimethylamine N-oxide (TMAO) respiratory system, is tightly controlled by the TorS-TorR phosphorelay system in response to TMAO availability. TorS is an unorthodox sensor that contains three phosphorylation sites and transphosphorylates TorR via a four-step phosphorelay, His443-->Asp723-->His850-->Asp(TorR). In this study, we provide genetic evidence that TorS can dephosphorylate phospho-TorR when TMAO is removed. Dephosphorylation probably occurs by a reverse phosphorelay, Asp(TorR)-->His850-->Asp723, since His850 and Asp723 are both essential in this process. By using reverse transcriptase PCR, we also show that TMAO removal results in shutoff of tor operon transcription in less than 2 min. Based on our results and on analogy to other phosphorelay signal transduction systems, we propose that reverse phosphotransfer could be a rapid and efficient mechanism to inactivate response regulators.
Laboratoire de Chimie Bactérienne, Institut de Biologie Structurale et Microbiologie, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France.
M
M
Ansaldi
C
C
Jourlin-Castelli
M
M
Lepelletier
L
L
Théraulaz
V
V
Méjean
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008744:Methylamines / Q000378:metabolism*; D009876:Operon; D010766:Phosphorylation; D010770:Phosphotransferases; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D008744:Methylamines; C089364:TorR protein, E coli; D014157:Transcription Factors; D010770:Phosphotransferases; C103806:TorS protein, E coli; C005855:trimethyloxamine