Signal-regulator interactions, genetic analysis of the effector binding site of xyls, the benzoate-activated positive regulator of Pseudomonas TOL plasmid meta-cleavage pathway operon

Ramos, Juan L.; Michán, Carmen; Rojo, Fernando; Dwyer, Daryl F.; Timmis, Kenneth N.

doi:10.1016/0022-2836(90)90358-s

Cited by 86 publications

(80 citation statements)

References 29 publications

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“…AraCfamily transcription regulators generally function as dimers to either activate or repress transcription at a given locus (57,58). The AraC family members canonically regulate genes involved in metabolism (e.g., AraC and XylS for regulation of arabinose and xylene/benzoate metabolism, respectively [59,60]) and/or virulence (61) (e.g., ExsA regulation of type III secretion in P. aeruginosa [62] and ToxT regulation of cholera toxin and the toxincoregulated pilus in Vibrio cholerae [63]). Evidence suggests that GbdR senses GB and dimethylglycine levels in the cell and induces transcription of genes involved in virulence, GB transport, GB catabolism, and detoxification of the catabolic byproducts, hydrogen peroxide and formaldehyde (48,56,(64)(65)(66)(67)(68) (Fig.…”

Section: Choline and Gb Import Versus De Novo Synthesismentioning

confidence: 99%

Homeostasis and Catabolism of Choline and Glycine Betaine: Lessons from Pseudomonas aeruginosa

Wargo

2013

Appl Environ Microbiol

156

121

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Most sequenced bacteria possess mechanisms to import choline and glycine betaine (GB) into the cytoplasm. The primary role of choline in bacteria appears to be as the precursor to GB, and GB is thought to primarily act as a potent osmoprotectant. Choline and GB may play accessory roles in shaping microbial communities, based on their limited availability and ability to enhance survival under stress conditions. Choline and GB enrichment near eukaryotes suggests a role in the chemical relationships between these two kingdoms, and some of these interactions have been experimentally demonstrated. While many bacteria can convert choline to GB for osmoprotection, a variety of soil-and water-dwelling bacteria have catabolic pathways for the multistep conversion of choline, via GB, to glycine and can thereby use choline and GB as sole sources of carbon and nitrogen. In these choline catabolizers, the GB intermediate represents a metabolic decision point to determine whether GB is catabolized or stored as an osmo-and stress protectant. This minireview focuses on this decision point in Pseudomonas aeruginosa, which aerobically catabolizes choline and can use GB as an osmoprotectant and a nutrient source. P. aeruginosa is an experimentally tractable and ecologically relevant model to study the regulatory pathways controlling choline and GB homeostasis in choline-catabolizing bacteria. The study of P. aeruginosa associations with eukaryotes and other bacteria also makes this a powerful model to study the impact of choline and GB, and their associated regulatory and catabolic pathways, on host-microbe and microbe-microbe relationships.

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Section: Choline and Gb Import Versus De Novo Synthesismentioning

confidence: 99%

Homeostasis and Catabolism of Choline and Glycine Betaine: Lessons from Pseudomonas aeruginosa

Wargo

2013

Appl Environ Microbiol

156

121

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“…Both C-and N-terminal parts can act independently (218,219). For example, mutations in both the C-and N-terminal regions of XylS can yield semiconstitutive mutants (203) or suppressors (143). This suggests there is some form of "cross talking" between the two domains, but the mechanism of this remains to be resolved.…”

Section: Structure and Conformationmentioning

confidence: 99%

“…However, 38 -RNAP uses exactly the same promoter region in the P m promoter as that used by 32 (136). Mutants can be obtained with mutations in the N-terminal domain of XylS which change the requirement of XylS for 38 to 70 (203). A large number of XylS/AraC members, including XylS itself, seem to require contact with ␣-CTD and with parts of the -factor in order to achieve full activation (15,53,116,117,131,220).…”

Section: Mechanisms Of Activationmentioning

confidence: 99%

Bacterial Transcriptional Regulators for Degradation Pathways of Aromatic Compounds

Tropel

Meer

2004

Microbiol Mol Biol Rev

345

338

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Human activities have resulted in the release and introduction into the environment of a plethora of aromatic chemicals. The interest in discovering how bacteria are dealing with hazardous environmental pollutants has driven a large research community and has resulted in important biochemical, genetic, and physiological knowledge about the degradation capacities of microorganisms and their application in bioremediation, green chemistry, or production of pharmacy synthons. In addition, regulation of catabolic pathway expression has attracted the interest of numerous different groups, and several catabolic pathway regulators have been exemplary for understanding transcription control mechanisms. More recently, information about regulatory systems has been used to construct whole-cell living bioreporters that are used to measure the quality of the aqueous, soil, and air environment. The topic of biodegradation is relatively coherent, and this review presents a coherent overview of the regulatory systems involved in the transcriptional control of catabolic pathways. This review summarizes the different regulatory systems involved in biodegradation pathways of aromatic compounds linking them to other known protein families. Specific attention has been paid to describing the genetic organization of the regulatory genes, promoters, and target operon(s) and to discussing present knowledge about signaling molecules, DNA binding properties, and operator characteristics, and evidence from regulatory mutants. For each regulator family, this information is combined with recently obtained protein structural information to arrive at a possible mechanism of transcription activation. This demonstrates the diversity of control mechanisms existing in catabolic pathways

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“…The range of effectors recognized by catabolic pathway regulators is typically larger than the range of substrates metabolized by the pathway (10)(11)(12)(13). To identify the range of aromatic compounds that activate transcription from P todX we measured induction by using the P todX ::lacZ fusion.…”

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confidence: 99%

The TodS–TodT two-component regulatory system recognizes a wide range of effectors and works with DNA-bending proteins

Lacal

Büsch

Guazzaroni

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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The TodS and TodT proteins form a previously unrecognized and highly specific two-component regulatory system in which the TodS sensor protein contains two input domains, each of which are coupled to a histidine kinase domain. This system regulates the expression of the genes involved in the degradation of toluene, benzene, and ethylbenzene through the toluene dioxygenase pathway. In contrast to the narrow substrate range of this catabolic pathway, the TodS effector profile is broad. TodS has basal autophosphorylation activity in vitro, which is enhanced by the presence of effectors. Toluene binds to TodS with high affinity (K d ‫؍‬ 684 ؎ 13 nM) and 1:1 stoichiometry. The analysis of the truncated variants of TodS reveals that toluene binds to the N-terminal input domain (K d ‫؍‬ 2.3 ؎ 0.1 M) but not to the C-terminal half. TodS transphosphorylates TodT, which binds to two highly similar DNA binding sites at base pairs ؊107 and ؊85 of the promoter. Integration host factor (IHF) plays a crucial role in the activation process and binds between the upstream TodT boxes and the ؊10 hexamer region. In an IHF-deficient background, expression from the tod promoter drops 8-fold. In vitro transcription assays confirmed the role determined in vivo for TodS, TodT, and IHF. A functional model is presented in which IHF favors the contact between the TodT activator, bound further upstream, and the ␣-subunit of RNA polymerase bound to the downstream promoter element. Once these contacts are established, the tod operon is efficiently transcribed.Pseudomonas ͉ sensor kinase ͉ toluene dioxygenase ͉ transcriptional regulator M any Pseudomonas putida strains are able to use benzene, toluene, and ethylbenzene as the sole carbon and energy source through the toluene dioxygenase (TOD) pathway (1). In this pathway, the aromatic hydrocarbons are oxidized to their corresponding substituted catechols, which are further metabolized to Krebs cycle intermediates (1, 2). The catabolic genes of the TOD pathway form the operon todXFC1C2BADEGIH, which is transcribed from a single promoter called P todX , located upstream from the todX gene (1-3). The todST genes are found downstream and form an independent operon that is expressed constitutively (2, 3).TodS and TodT have been proposed to form a two-component regulatory system (TCS) that regulates the tod catabolic operon in P. putida F1 (3). TodT shows all of the characteristics of a response regulator, whereas sequence-based domain predictions indicate that the 108-kDa TodS belongs to a family of sensor histidine kinases that have not been studied at the biochemical level. TodS is predicted to comprise two supradomains, each containing a PAS͞PAC sensory domain and a histidine kinase domain. The supradomains are separated by the receiver domain of a response regulator. In contrast to other histidine kinases, TodS apparently lacks transmembrane regions (3). The mode of action of this previously unrecognized type of histidine kinase has yet to be established. On the basis of moderate sequence simil...

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Signal-regulator interactions, genetic analysis of the effector binding site of xyls, the benzoate-activated positive regulator of Pseudomonas TOL plasmid meta-cleavage pathway operon

Cited by 86 publications

References 29 publications

Homeostasis and Catabolism of Choline and Glycine Betaine: Lessons from Pseudomonas aeruginosa

Homeostasis and Catabolism of Choline and Glycine Betaine: Lessons from Pseudomonas aeruginosa

Bacterial Transcriptional Regulators for Degradation Pathways of Aromatic Compounds

The TodS–TodT two-component regulatory system recognizes a wide range of effectors and works with DNA-bending proteins

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