Modelled-Microgravity Reduces Virulence Factor Production in through Downregulation of -Dependent Quorum Sensing.

Bacterial contamination during space missions is problematic for human health and damages filters and other vital support systems. is both a human commensal and an opportunistic pathogen that colonizes human tissues and causes acute and chronic infections. Virulence and colonization factors are positively and negatively regulated, respectively, by bacterial cell-to-cell communication (quorum sensing) via the (accessory gene regulator) system.

Conformational analysis and interaction of the transmembrane peptidase AgrB with its AgrD propeptide substrate.

Virulence gene expression in the human pathogen, is regulated by the (accessory gene regulator) quorum sensing (QS) system which is conserved in diverse Gram-positive bacteria. The QS signal molecule is an autoinducing peptide (AIP) generated via the initial processing of the AgrD pro-peptide by the transmembrane peptidase AgrB. Since structural information for AgrB and AgrBD interactions are lacking, we used homology modelling and molecular dynamics (MD) annealing to characterise the conformations of AgrB and AgrD in model membranes and in solution.

A Pseudomonas aeruginosa PQS quorum-sensing system inhibitor with anti-staphylococcal activity sensitizes polymicrobial biofilms to tobramycin.

As single- and mixed-species biofilms, Staphylococcus aureus and Pseudomonas aeruginosa cause difficult-to-eradicate chronic infections. In P. aeruginosa, pseudomonas quinolone (PQS)-dependent quorum sensing regulates virulence and biofilm development that can be attenuated via antagonists targeting the transcriptional regulator PqsR (MvfR).

Detection of Agr-Type Autoinducing Peptides Produced by Staphylococcus aureus.

Strains of the Gram-positive pathogen Staphylococcus aureus can be divided into four quorum sensing (QS) groups. Membership of each group is defined by the amino acid sequence of the autoinducing peptide (AIP) QS signal molecule that is encoded within the agrBDCA genetic locus and specifically within agrD. This chapter describes the use of simple, in-cell, lux-based, bio-reporters that can be used to identify/confirm the specific agr group to which a particular S.

5-Hydroxyethyl-3-tetradecanoyltetramic acid represents a novel treatment for intravascular catheter infections due to Staphylococcus aureus.

Objectives: Biofilm infections of intravascular catheters caused by Staphylococcus aureus may be treated with catheter lock solutions (CLSs). Here we investigated the antibacterial activity, cytotoxicity and CLS potential of 5-hydroxyethyl-3-tetradecanoyltetramic acid (5HE-C14-TMA) compared with the related compounds 3-tetradecanoyltetronic (C14-TOA) and 3-tetradecanoylthiotetronic (C14-TTA), which are variants of quorum sensing signalling molecules produced by Pseudomonas aeruginosa .

Methods: Antibacterial activity and mechanism of action of 5HE-C14-TMA, C14-TOA and C14-TTA were determined via MIC, bacterial killing, membrane potential and permeability assays.

Targeting Staphylococcus aureus quorum sensing with nonpeptidic small molecule inhibitors.

A series of 3-oxo-C12-HSL, tetramic acid, and tetronic acid analogues were synthesized to gain insights into the structural requirements for quorum sensing inhibition in Staphylococcus aureus. Compounds active against agr were noncompetitive inhibitors of the autoinducing peptide (AIP) activated AgrC receptor, by altering the activation efficacy of the cognate AIP-1. They appeared to act as negative allosteric modulators and are exemplified by 3-tetradecanoyltetronic acid 17, which reduced nasal cell colonization and arthritis in a murine infection model.

Evolution and multiplicity of arginine decarboxylases in polyamine biosynthesis and essential role in Bacillus subtilis biofilm formation.

Arginine decarboxylases (ADCs; EC 4.1.1.

The sensitivity of Bacillus subtilis to diverse antimicrobial compounds is influenced by Abh.

Abh is a transition state regulator of Bacillus subtilis that controls biofilm formation and the production of several diverse antimicrobial compounds. Using a high-throughput non-biased technique, we show for the first time that Abh influences the sensitivity of B. subtilis to diverse antimicrobial compounds.

SigmaX is involved in controlling Bacillus subtilis biofilm architecture through the AbrB homologue Abh.

A characteristic feature of biofilm formation is the production of a protective extracellular polymeric matrix. In the gram-positive bacterium Bacillus subtilis, the biofilm matrix is synthesized by the products of the epsABCDEFGHIJKLMNO operon (hereafter called the eps operon) and yqxM-sipW-tasA loci. Transcription from these operons is repressed by two key regulators, AbrB and SinR.

A pivotal role for the response regulator DegU in controlling multicellular behaviour.

Bacteria control multicellular behavioural responses, including biofilm formation and swarming motility, by integrating environmental cues through a complex regulatory network. Heterogeneous gene expression within an otherwise isogenic cell population that allows for differentiation of cell fate is an intriguing phenomenon that adds to the complexity of multicellular behaviour. This review focuses on recent data about how DegU, a pleiotropic response regulator, co-ordinates multicellular behaviour in Bacillus subtilis.

DegU and Spo0A jointly control transcription of two loci required for complex colony development by Bacillus subtilis.

Biofilm formation is an example of a multicellular process which depends on cooperative behavior and differentiation within a bacterial population. Our findings indicate that there is a complex feedback loop that maintains the stoichiometry of the extracellular matrix and other proteins required for complex colony development by Bacillus subtilis. Analysis of the transcriptional regulation of two DegU-activated genes that are required for complex colony development by B.