Dataset Information

Characterization and complete sequence of lactonase enzyme from Bacillus weihenstephanensis isolate P65 with potential activity against acyl homoserine lactone signal molecules.

ABSTRACT: Acyl homoserine lactones (AHLs) are the most common class of quorum sensing signal molecules (autoinducers) that have been reported to be essential for virulence of many relevant pathogenic bacteria such as Pseudomonas aeruginosa. New approach for controlling infections of such bacteria is through quorum quenching. In this study, the acyl homoserine lactone inhibitory activity of the crude enzyme from a Bacillus weihenstephanensis-isolate P65 was characterized. The crude enzyme was found to have relatively high thermal stability and was stable in pH range 6 to 9. The crude enzyme extract was found to have lactonase activity of 36.3 U/mg total protein. Maximum enzyme activity was achieved within a range of 28-50°C and pH 6-9. None of the metals used enhanced the activity neither did EDTA inhibit it. However, a concentration of 10 mM Fe(+2) reduced the activity to 73.8%. Catalytic activity and kinetic constants were determined using hexanoyl homoserine lactone as a substrate. Studying enzyme substrate specificity using synthetic standard signals displayed broad spectrum of activity. The enzyme was found to be constitutive. Isolation and complete nucleotide sequence of the respective lactonase gene were done and submitted to the Genbank database under accession code KC823046.

SUBMITTER: Sakr MM

PROVIDER: S-EPMC3722983 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Characterization and complete sequence of lactonase enzyme from Bacillus weihenstephanensis isolate P65 with potential activity against acyl homoserine lactone signal molecules.

Sakr Masarra Mohammed MM Aboshanab Khaled Mohamed Anwar KM Aboulwafa Mohammad Mabrouk MM Hassouna Nadia Abdel-Haleem NA

BioMed research international 20130709

Acyl homoserine lactones (AHLs) are the most common class of quorum sensing signal molecules (autoinducers) that have been reported to be essential for virulence of many relevant pathogenic bacteria such as Pseudomonas aeruginosa. New approach for controlling infections of such bacteria is through quorum quenching. In this study, the acyl homoserine lactone inhibitory activity of the crude enzyme from a Bacillus weihenstephanensis-isolate P65 was characterized. The crude enzyme was found to have ...[more]

PMID: 23936779

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Project description:The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of airway infection in cystic fibrosis (CF) patients. P. aeruginosa employs several hierarchically arranged and interconnected quorum sensing (QS) regulatory circuits to produce a battery of virulence factors such as elastase, phenazines, and rhamnolipids. The QS transcription factor LasR sits atop this hierarchy and activates the transcription of dozens of genes, including that encoding the QS regulator RhlR. Paradoxically, inactivating lasR mutations are frequently observed in isolates from CF patients with chronic P. aeruginosa infections. In contrast, mutations in rhlR are rare. We have recently shown that in CF isolates, the QS circuitry is often rewired such that RhlR acts in a LasR-independent manner. To begin understanding how QS activity differs in this rewired background, we characterized QS activation and RhlR-regulated gene expression in P. aeruginosa E90, a LasR-null, RhlR-active chronic infection isolate. In this isolate, RhlR activates the expression of 53 genes in response to increasing cell density. The genes regulated by RhlR include several that encode virulence factors. Some, but not all, of these genes are present in the QS regulon described in the well-studied laboratory strain PAO1. We also demonstrate that E90 produces virulence factors at similar concentrations as PAO1, and in E90, RhlR plays a significant role in mediating cytotoxicity in a three-dimensional lung epithelium cell model. These data illuminate a rewired LasR-independent RhlR regulon in chronic infection isolates and suggest further investigation of RhlR as a possible target for therapeutic development in chronic infections.IMPORTANCE Pseudomonas aeruginosa is a prominent cystic fibrosis (CF) pathogen that uses quorum sensing (QS) to regulate virulence. In laboratory strains, the key QS regulator is LasR. Many isolates from patients with chronic CF infections appear to use an alternate QS circuitry in which another transcriptional regulator, RhlR, mediates QS. We show that a LasR-null CF clinical isolate engages in QS through RhlR and remains capable of inducing cell death in an in vivo-like lung epithelium cell model. Our findings support the notion that LasR-null clinical isolates can engage in RhlR QS and highlight the centrality of RhlR in chronic P. aeruginosa infections.

Dataset Information

Characterization and complete sequence of lactonase enzyme from Bacillus weihenstephanensis isolate P65 with potential activity against acyl homoserine lactone signal molecules.

Publications

Characterization and complete sequence of lactonase enzyme from Bacillus weihenstephanensis isolate P65 with potential activity against acyl homoserine lactone signal molecules.

Similar Datasets

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