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alignment of chromate efflux amino acid sequences and generated the phylogenetic trees. DT participated in study design and coordination. heptaminol AK participated in study design and coordination. All authors participated in drafting the manuscript. All authors read and approved the final manuscript.”
“Background Several bacteria utilize a cell-cell communication system called quorum sensing to coordinate diverse behaviors in response to population density . This quorum sensing process is based on the generation of small signaling molecules by means of specific synthases. These signaling molecules accumulate into the extracellular environment and when a certain threshold concentration is reached, the bacteria detect and respond to this signal by altering their gene expression. Although several quorum sensing systems are known, the synthase highly conserved in many both Gram-negative and Gram-positive bacterial species is the quorum sensing synthase LuxS [2, 3]. This enzyme catalyzes the conversion of S-ribosylhomocysteine to 4,5-dihydroxy-2,3-pentanedione (DPD) and homocysteine . The unstable DPD spontaneously cyclizes into a family of interconverting molecules, collectively referred to as autoinducer-2 (AI-2) . One of the first species reported to produce and respond to AI-2 resulting in expression of its luminescence genes is the marine pathogen Vibrio harveyi .