Locations of Mapped Genes:
|Superclasses:||Signal transduction pathways|
In the absence of oxygen E.coli K-12 is able to generate energy using a variety of different substances as terminal electron acceptors. One such substance is trimethylamine N-oxide (TMAO) which, under anaerobic conditions, is reduced to TMA by the action of the periplasmic molybdoprotein TMAO reductase, encoded by the TorCA genes. TorSR is the two-component signal transduction system that controls the cells ability to use TMAO as an alternate electron acceptor. TorS is the membrane associated sensor kinase which detects the presence of trimethylamine N-oxide (TMAO) in the medium and phosphorylates its cognate response regulator, TorR. Thus activated, phosphorylated TorR binds to a region upstream of TorC and induces the torCAD operon. TorR has also been shown to regulate the expression of genes involved in the response to extreme pH leading to the suggestion that the TorSR system also triggers alkaline stress defence mechanisms to counteract the increasing pH resulting from TMA production.
The periplasmic TorT protein acts upstream of the TorSR two-component system. TorT binds to TMAO and interacts with the periplasmic domain of TorS thus suggesting that the TorS activating signal may be a TMAO-TorT complex.
Jourlin96a: Jourlin C, Bengrine A, Chippaux M, Mejean V (1996). "An unorthodox sensor protein (TorS) mediates the induction of the tor structural genes in response to trimethylamine N-oxide in Escherichia coli." Mol Microbiol 1996;20(6);1297-306. PMID: 8809780
Yamamoto05a: Yamamoto K, Hirao K, Oshima T, Aiba H, Utsumi R, Ishihama A (2005). "Functional characterization in vitro of all two-component signal transduction systems from Escherichia coli." J Biol Chem 280(2);1448-56. PMID: 15522865
Ansaldi00: Ansaldi M, Simon G, Lepelletier M, Mejean V (2000). "The TorR high-affinity binding site plays a key role in both torR autoregulation and torCAD operon expression in Escherichia coli." J Bacteriol 2000;182(4);961-6. PMID: 10648521
Ansaldi01: Ansaldi M, Jourlin-Castelli C, Lepelletier M, Theraulaz L, Mejean V (2001). "Rapid dephosphorylation of the TorR response regulator by the TorS unorthodox sensor in Escherichia coli." J Bacteriol 2001;183(8);2691-5. PMID: 11274133
Bordi03: Bordi C, Theraulaz L, Mejean V, Jourlin-Castelli C (2003). "Anticipating an alkaline stress through the Tor phosphorelay system in Escherichia coli." Mol Microbiol 48(1);211-23. PMID: 12657056
Hirakawa03: Hirakawa H, Nishino K, Hirata T, Yamaguchi A (2003). "Comprehensive studies of drug resistance mediated by overexpression of response regulators of two-component signal transduction systems in Escherichia coli." J Bacteriol 185(6);1851-6. PMID: 12618449
Jourlin96: Jourlin C, Simon G, Pommier J, Chippaux M, Mejean V (1996). "The periplasmic TorT protein is required for trimethylamine N-oxide reductase gene induction in Escherichia coli." J Bacteriol 1996;178(4);1219-23. PMID: 8576063
Jourlin97: Jourlin C, Ansaldi M, Mejean V (1997). "Transphosphorylation of the TorR response regulator requires the three phosphorylation sites of the TorS unorthodox sensor in Escherichia coli." J Mol Biol 1997;267(4);770-7. PMID: 9135110
Pascal91: Pascal MC, Lepelletier M, Giordano G, Chippaux M (1991). "A regulatory mutant of the trimethylamine N-oxide reductase of Escherichia coli K12." FEMS Microbiol Lett 62(2-3);297-300. PMID: 2040436
Simon94: Simon G, Mejean V, Jourlin C, Chippaux M, Pascal MC (1994). "The torR gene of Escherichia coli encodes a response regulator protein involved in the expression of the trimethylamine N-oxide reductase genes." J Bacteriol 1994;176(18);5601-6. PMID: 8083154
Simon95: Simon G, Jourlin C, Ansaldi M, Pascal MC, Chippaux M, Mejean V (1995). "Binding of the TorR regulator to cis-acting direct repeats activates tor operon expression." Mol Microbiol 1995;17(5);971-80. PMID: 8596446
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