BACKGROUND AND OBJECTIVES In present study we aimed to clone the luxI gene encoding N-acyl-homoserine synthase detected in clinical isolates of Acinetobacter baumannii and study its expression in Escherichia coli transformants. MATERIALS AND METHODS Four A. baumannii hospital strains which demonstrated strong biofilm activity were selected in this investigation. The presence of luxI gene was ...

Synthesis of the Vibrio fischeri autoinducer, a signal involved in the cell density-dependent activation of bioluminescence, is directed by the luxI gene product. The LuxI protein catalyzes the synthesis of N-acyl-homoserine lactones from S-adenosylmethionine and acylated-acyl carrier protein. We have gained an appreciation of the LuxI regions and amino acid residues involved in autoinducer syn...

Many pathogenic bacteria use quorum sensing (QS) systems to regulate the expression of virulence genes in a density-dependent manner. In one widespread QS paradigm the enzyme LuxI generates a small diffusible molecule of the acyl-homoserine lactone (AHL) family; high cell densities lead to high AHL levels; AHL binds the transcription factor LuxR, triggering it to activate gene expression at a v...

Many Proteobacteria govern responses to changes in cell density by using acyl-homoserine lactone (AHL) quorum-sensing (QS) signaling. Similar to the LuxI-LuxR system described in Vibrio fischeri, a minimal AHL QS circuit comprises a pair of genes, a luxI-type synthase gene encoding an enzyme that synthesizes an AHL and a luxR-type AHL-responsive transcription regulator gene. In most bacteria th...

objectives: in present study we aimed to clone the lux i gene encoding n-acyl-homoserine synthase detected in biofilm forming clinical isolates of acinetobacter baumannii and study its expression in escherichia coli transformants. materials and methods: four a. baumannii hospital strains which demonstrated strong biofilm activity were selected in this investigation. the presence of lux i gene w...

The effect of a mutation in luxI (autoinducer synthetase gene) on transcription of luxR in the cloned Vibrio fischeri lux system (luxR, luxICDABE) was examined in Escherichia coli. For the luxI mutant, transcription from the luxR promoter (monitored with beta-galactosidase levels from a luxR::lacZ fusion, with LuxR supplied in trans) decreased fivefold, to levels of the luxI+ strain, only in th...

Communication among bacterial cells through quorum-sensing (QS) systems is used to regulate ecologically and medically important traits, including virulence to hosts. QS is widespread in bacteria; it has been demonstrated experimentally in diverse phylogenetic groups, and homologs to the implicated genes have been discovered in a large proportion of sequenced bacterial genomes. The widespread d...

The process of intercellular communication among bacteria, termed quorum sensing (QS), is mediated by small diffusible molecules known as the autoinducers. QS allows the population to react to the change of cell density in unison, in processes such as biofilm formation, plasmid conjugation, virulence, motility and root nodulation. In Gram-negative proteobacteria, N-acyl homoserine lactone (AHL)...

Quorum sensing is a mechanism for regulating proteobacterial gene expression in response to changes in cell population. In proteobacteria, N-acyl homoserine lactone (AHL) appears to be the most widely used signalling molecules in mediating, among others, the production of extracellular virulence factors for survival. In this work, the genome of B. cepacia strain GG4, a plasmid-free strain capab...

Acylhomoserine lactones, which serve as quorum-sensing signals in gram-negative bacteria, are produced by members of the LuxI family of synthases. LuxI is a Vibrio fischeri enzyme that catalyzes the synthesis of N-(3-oxohexanoyl)-L-homoserine lactone from an acyl-acyl carrier protein and S-adenosylmethionine. Another V. fischeri gene, ainS, directs the synthesis of N-octanoylhomoserine lactone....