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 rece...

Vaulted structure has been in use for nearly 4000 years and believed to have been studied by scientists and builders for nearly 2000 years. There are few publications about the geometry and constructional aspects of arches and vaults before Renaissance age. One of the most interesting works on this subject belongs to Jamshid Kashani known as a mathematician. Ghiayth Al-Din Kashani, has made so...

In Gram-negative bacteria, quorum sensing is mediated by N-acylhomoserine lactones (AHL) to regulate different biological functions, including production of virulence factors. Quorum quenching refers to the interruption of quorum sensing, and the most attractive way is to degrade the AHL molecules. With the aim of isolating soil bacteria capable of blocking quorum sensing by inactivating AHL, a...

N-acyl homoserine lactone (AHL)-mediated quorum sensing by bacteria regulates traits that are involved in symbiotic, pathogenic and surface-associated relationships between microbial populations and their plant hosts. Recent advances demonstrate deviations from the classic LuxR/LuxI paradigm, which was first developed in Vibrio. For example, LuxR homologs can repress as well as activate gene ex...

In gram-negative bacteria, many important changes in gene expression and behavior are regulated in a population density-dependent fashion by N-acyl homoserine lactone (AHL) signal molecules. Exudates from pea (Pisum sativum) seedlings were found to contain several separable activities that mimicked AHL signals in well-characterized bacterial reporter strains, stimulating AHL-regulated behaviors...

Brucella quorum sensing has been described as an important regulatory system controlling crucial virulence determinants such as the VirB type IV secretion system and the flagellar genes. However, the basis of quorum sensing, namely the production of autoinducers in Brucella has been questioned. Here, we report data obtained from the use of a genetic tool allowing the in situ detection of long-c...

The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL) are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and b...

hashemiat are title of eight religious, sociopolitical and revolutionary odes that have been verified by kumait ibn zeyd asadi; in fact these odes are considered as the first and foremost work of him and they have been versified approximately fifteen or twenty years after martyrdom of imam hossein (pbuh) within the suffocating and oppressive ruling period of umayyads and they were propagated pr...

During quorum sensing in the plant pathogen Pantoea stewartii subsp. stewartii, EsaI, an acyl-homoserine lactone (AHL) synthase, and the transcription factor EsaR coordinately control capsular polysaccharide production. The capsule is expressed only at high cell density when AHL levels are high, leading to inactivation of EsaR. In lieu of detailed structural information, the precise mechanism w...

N-Acylhomoserine lactone (AHL)-acylase (also known as amidase or amidohydrolase) is a class of enzyme that belongs to the Ntn-hydrolase superfamily. As the name implies, AHL-acylases are capable of hydrolysing AHLs, the most studied signaling molecules for quorum sensing in Gram-negative bacteria. Enzymatic degradation of AHLs can be beneficial in attenuating bacterial virulence, which can be e...