Crystal structure of the quorum sensing protein TraM and its interaction with the transcriptional regulator TraR

Vannini, Alessandro; Volpari, Cinzia; Marco, Stefania Di

doi:10.1107/s0108767304097296

Cited by 13 publications

(19 citation statements)

References 3 publications

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“…The antiactivator protein, TraM, inhibits the DNA binding of TraR (30,31). Structures of the TraR-3OC8-HSL-TraM complex showed that TraM binds between the LBD and DBD in a symmetric configuration, making numerous contacts with DBD, LBD, and the linker between them, which places the DBDs in a position that is incompetent to bind to DNA (13,(32)(33)(34). Because TraM can form a complex with TraR while it is simultaneously bound to DNA (34), it is quite unlikely that TraR adopts a crosssubunit architecture, and indeed the linker of TraR probably evolved to bind to TraM and not necessarily to make the extensive interactions with the LBD or DBDs that have been observed in the QscR or CviR structures (16).…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of QscR, aPseudomonas aeruginosaquorum sensing signal receptor

Lintz

Oinuma

Wysoczynski

et al. 2011

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

111

131

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Acyl-homoserine lactone (AHL) quorum sensing controls gene expression in hundreds of Proteobacteria including a number of plant and animal pathogens. Generally, the AHL receptors are members of a family of related transcription factors, and although they have been targets for development of antivirulence therapeutics there is very little structural information about this class of bacterial receptors. We have determined the structure of the transcription factor, QscR, bound to N-3-oxo-dodecanoyl-homoserine lactone from the opportunistic human pathogen Pseudomonas aeruginosa at a resolution of 2.55 Å. The ligand-bound QscR is a dimer with a unique symmetric “cross-subunit” arrangement containing multiple dimerization interfaces involving both domains of each subunit. The QscR dimer appears poised to bind DNA. Predictions about signal binding and dimerization contacts were supported by studies of mutant QscR proteins in vivo. The acyl chain of the AHL is in close proximity to the dimerization interfaces. Our data are consistent with an allosteric mechanism of signal transmission in the regulation of DNA binding and thus virulence gene expression.

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Section: Discussionmentioning

confidence: 99%

Crystal structure of QscR, aPseudomonas aeruginosaquorum sensing signal receptor

Lintz

Oinuma

Wysoczynski

et al. 2011

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

111

131

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“…Biochemical studies suggest that the TraM homodimer dissociates in order to form a heterodimer with monomeric TraR, in a 1:1 stoichiometry (12). A second report suggested a multimeric interaction involving two TraR and two TraM dimers (145). The actual mode of binding and inactivation of TraR function by TraM can be confirmed only upon studying the crystal structure of a TraR-TraM complex (12,110,145).…”

Section: Negative Regulation Of Quorum Sensing Antiactivator Proteinsmentioning

confidence: 99%

Messing with Bacterial Quorum Sensing

Gonzalez

Keshavan

2006

Microbiol Mol Biol Rev

366

232

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SUMMARY Quorum sensing is widely recognized as an efficient mechanism to regulate expression of specific genes responsible for communal behavior in bacteria. Several bacterial phenotypes essential for the successful establishment of symbiotic, pathogenic, or commensal relationships with eukaryotic hosts, including motility, exopolysaccharide production, biofilm formation, and toxin production, are often regulated by quorum sensing. Interestingly, eukaryotes produce quorum-sensing-interfering (QSI) compounds that have a positive or negative influence on the bacterial signaling network. This eukaryotic interference could result in further fine-tuning of bacterial quorum sensing. Furthermore, recent work involving the synthesis of structural homologs to the various quorum-sensing signal molecules has resulted in the development of additional QSI compounds that could be used to control pathogenic bacteria. The creation of transgenic plants that express bacterial quorum-sensing genes is yet another strategy to interfere with bacterial behavior. Further investigation on the manipulation of quorum-sensing systems could provide us with powerful tools against harmful bacteria.

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“…Recently, a number of authors reported that, like TraR, TraM also forms a dimer [25][26][27]. The stoichiometry of the reaction between TraR and TraM, however, remains controversial [25][26][27]. In our model we follow the original hypothesis of Swiderska et al [24], which assumes that the complex consists of one TraRd and one monomer of TraM.…”

Section: Synopsismentioning

confidence: 95%

“…TraM effectively sequesters TraRd through the formation of a very stable complex in which TraRd is unable to bind DNA [23,24]. Recently, a number of authors reported that, like TraR, TraM also forms a dimer [25][26][27]. The stoichiometry of the reaction between TraR and TraM, however, remains controversial [25][26][27].…”

Section: Synopsismentioning

confidence: 99%

Transition to Quorum Sensing in an Agrobacterium Population: A Stochastic Model

Goryachev¹,

Toh²,

Wee³

et al. 2005

PLoS Comp Biol

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Understanding of the intracellular molecular machinery that is responsible for the complex collective behavior of multicellular populations is an exigent problem of modern biology. Quorum sensing, which allows bacteria to activate genetic programs cooperatively, provides an instructive and tractable example illuminating the causal relationships between the molecular organization of gene networks and the complex phenotypes they control. In this work we-to our knowledge for the first time-present a detailed model of the population-wide transition to quorum sensing using the example of Agrobacterium tumefaciens. We construct a model describing the Ti plasmid quorum-sensing gene network and demonstrate that it behaves as an ''on-off'' gene expression switch that is robust to molecular noise and that activates the plasmid conjugation program in response to the increase in autoinducer concentration. This intracellular model is then incorporated into an agent-based stochastic population model that also describes bacterial motion, cell division, and chemical communication. Simulating the transition to quorum sensing in a liquid medium and biofilm, we explain the experimentally observed gradual manifestation of the quorum-sensing phenotype by showing that the transition of individual model cells into the ''on'' state is spread stochastically over a broad range of autoinducer concentrations. At the same time, the population-averaged values of critical autoinducer concentration and the threshold population density are shown to be robust to variability between individual cells, predictable and specific to particular growth conditions. Our modeling approach connects intracellular and population scales of the quorum-sensing phenomenon and provides plausible answers to the long-standing questions regarding the ecological and evolutionary significance of the phenomenon. Thus, we demonstrate that the transition to quorum sensing requires a much higher threshold cell density in liquid medium than in biofilm, and on this basis we hypothesize that in Agrobacterium quorum sensing serves as the detector of biofilm formation.

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Crystal structure of the quorum sensing protein TraM and its interaction with the transcriptional regulator TraR

Cited by 13 publications

References 3 publications

Crystal structure of QscR, aPseudomonas aeruginosaquorum sensing signal receptor

Crystal structure of QscR, aPseudomonas aeruginosaquorum sensing signal receptor

Messing with Bacterial Quorum Sensing

Transition to Quorum Sensing in an Agrobacterium Population: A Stochastic Model

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