Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes
            <i>hcnABC</i>
            by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in
            <i>Pseudomonas aeruginosa</i>

Pessi, Gabriella; Haas, Dieter

doi:10.1128/jb.182.24.6940-6949.2000

Cited by 248 publications

(267 citation statements)

References 59 publications

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“…However, there are only few and contradictory reports regarding QS regulation of volatile production. Whereas for hydrogen cyanide in Pseudomonas and Chromobacterium species it was concluded to be QS regulated (Pessi and Haas, 2000;Blom et al, 2011), for B. ambifaria, production of volatiles appeared not to be controlled by QS as the volatile profiles of the wild-type and the QS mutant were very similar (Groenhagen et al, 2013). Future challenges are therefore to further elucidate the large chemical diversity of microbial volatiles, to discover regulatory pathways and genes involved in the biosynthesis of volatiles in soil bacteria and fungi, to determine biologically relevant concentrations and to resolve the importance of volatiles in ecosystem processes.…”

Section: Discussionmentioning

confidence: 99%

Volatile affairs in microbial interactions

et al. 2015

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Microorganisms are important factors in shaping our environment. One key characteristic that has been neglected for a long time is the ability of microorganisms to release chemically diverse volatile compounds. At present, it is clear that the blend of volatiles released by microorganisms can be very complex and often includes many unknown compounds for which the chemical structures remain to be elucidated. The biggest challenge now is to unravel the biological and ecological functions of these microbial volatiles. There is increasing evidence that microbial volatiles can act as infochemicals in interactions among microbes and between microbes and their eukaryotic hosts. Here, we review and discuss recent advances in understanding the natural roles of volatiles in microbe-microbe interactions. Specific emphasis will be given to the antimicrobial activities of microbial volatiles and their effects on bacterial quorum sensing, motility, gene expression and antibiotic resistance.

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Section: Discussionmentioning

confidence: 99%

Volatile affairs in microbial interactions

et al. 2015

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“…In P. aeruginosa, environmental conditions such as nutrient availability have also been shown to affect the expression of QS genes (Withers et al, 2001;Albus et al, 1997). Cyanide production, which is related to QS in P. aeruginosa, increased under low oxygen concentration (Pessi & Haas, 2000). Furthermore, Bollinger et al (2001) found an increased expression of lasI under conditions of iron deprivation in uncontrolled shake-flask culture.…”

Section: Introductionmentioning

confidence: 97%

Expression of the quorum-sensing regulatory protein LasR is strongly affected by iron and oxygen concentrations in cultures of Pseudomonas aeruginosa irrespective of cell density

et al. 2005

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Expression of the quorum-sensing regulatory protein LasR is strongly affected by iron and oxygen concentrations in cultures of Pseudomonas aeruginosa irrespective of cell density The expression of the transcriptional regulatory protein LasR, a main component of the quorum-sensing (QS) system in Pseudomonas aeruginosa, was recently found to be sensitive to several environmental factors in addition to its dependency on cell density. However, the inherent effects of the different factors have seldom been separately demonstrated due to concurrent changes of culture conditions in typical experimental settings. Furthermore, the interplays of the different factors are unknown. In this work, the effects and interplay of iron concentration and dissolved oxygen tension (pO 2 ) on the expression of lasR in P. aeruginosa were studied in defined growth media with varied iron concentration and pO 2 values in computer-controlled batch and continuous cultures. b-Galactosidase activity in a recombinant P. aeruginosa PAO1 (NCCB 2452) strain with a lasRp-lacZ fusion was used as a reporter for lasR expression. In batch culture with a constant pO 2 <10 % air saturation, a strong correlation between the exhaustion of iron and the increase of lasR expression was observed. In continuous culture with nearly constant cell density but varied pO 2 values, lasR expression generally increased with increasing oxidative stress with the exception of growth under O 2 -limited conditions (pO 2 <0 %). Under O 2 limitation, the expression of lasR strongly depended on the concentration of iron. It showed a nearly twofold increase in cells grown under iron deprivation in comparison with cells grown in iron-replete conditions and reached the expression level seen at high oxidative stress. A preliminary proteomic analysis was carried out for extracellular proteins in samples from batch cultures grown under different iron concentrations. Several of the extracellular proteins (e.g. AprA, LasB, PrpL) which were up-regulated under iron-limited conditions were found to be QS regulated proteins. Thus, this study clearly shows the links between QS and genes involved in iron and oxygen regulation in P. aeruginosa. INTRODUCTIONPseudomonas aeruginosa, a Gram-negative opportunistic human pathogen, is often found in nosocomial infections. In particular, it can cause chronic pulmonary infection of cystic fibrosis patients, leading to a high mortality rate due to the formation of virulence factors and the inappropriate host response (Hybiske et al., 2004;Wolfgang et al., 2004;Lyczak et al., 2002). In P. aeruginosa, the formation of numerous virulence factors is controlled to a large extent by a mechanism called quorum sensing (QS) (Fuqua & Greenberg, 1998;Wagner et al., 2003;Schuster et al., 2003;Hentzer et al., 2003;Juhas et al., 2004). Two major genetic components of QS, the las and rhl systems, have been identified in P. aeruginosa. The las system consists of LasR, a transcriptional regulatory protein, and LasI, the autoinducer synthase that controls the producti...

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“…Target promoters respond to each system with varying degrees of specificity (8,12), but the sequence determinants for this specificity are not known. Genetic evidence suggests that LasR and RhlR bind to conserved palindromic sequences of some quorum-controlled promoters (12)(13)(14)(15), and more such sites have been located upstream of other quorum-controlled genes (7,8). These so-called las-rhl box-like sequences show similarity to the lux box, which is the promoter element required for quorum control of the V. fischeri luminescence genes (16).…”

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confidence: 99%

Promoter specificity in Pseudomonas aeruginosa quorum sensing revealed by DNA binding of purified LasR

Schuster

Urbanowski

Greenberg

2004

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

265

357

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Along with their cognate acyl-homoserine lactone signals, the quorum sensing regulators LasR and RhlR control the expression of hundreds of genes in the opportunistic human pathogen Pseudomonas aeruginosa. This extensive, overlapping regulatory network affords the opportunity to systematically investigate the sequence requirements and specificity determinants of large families of target promoters. Many of the P. aeruginosa quorum-controlled genes possess conserved palindromic promoter elements predicted to be binding sites for either one or both transcriptional regulators, but biochemical proof has not been reported. We have purified native LasR and characterized binding to various quorumcontrolled promoters in vitro. Purified LasR was a dimer in solution that irreversibly bound two molecules of 3-oxo-C12-homoserine lactone. LasR bound several las-responsive promoters specifically and with high affinity, interacting cooperatively with some promoters and noncooperatively with others. LasR recognized some, but not all, of the predicted binding sites, and also bound to several unexpected sites. In contrast to predictions from genetic data, we found that the recognition sequences of las-specific promoters showed little overall sequence conservation and did not require dyad symmetry. We found distinct differences in sequence composition between las-specific noncooperative, las-specific cooperative, and rhl-responsive promoters. These results provide the basis for defining promoter specificity elements in P. aeruginosa quorum sensing. Insights into the molecular mechanism of LasR function have implications for the development of quorum-sensing targeted antivirulence compounds.bacterial signaling ͉ cell communication ͉ homoserine lactone ͉ gene regulation

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Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes hcnABC by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in Pseudomonas aeruginosa

Cited by 248 publications

References 59 publications

Volatile affairs in microbial interactions

Volatile affairs in microbial interactions

Expression of the quorum-sensing regulatory protein LasR is strongly affected by iron and oxygen concentrations in cultures of Pseudomonas aeruginosa irrespective of cell density

Promoter specificity in Pseudomonas aeruginosa quorum sensing revealed by DNA binding of purified LasR

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