Disease relevance of luxS

• It was surprising, however, that so few genes were affected by luxS deletion in this E. coli K-12 strain under these conditions [1].
• The luxS gene recently shown to be responsible for production of autoinducer in the Vibrio harveyi and E. coli quorum-sensing systems is responsible for regulation of the LEE operons, as shown by the mutation and complementation of the luxS gene [2].
• Consistent with this idea, we have shown that many species of Gram-negative and Gram-positive bacteria produce AI-2 and, in every case, production of AI-2 is dependent on the function encoded by the luxS gene [3].
• Detection of a luxS-signaling molecule in Bacillus anthracis [4].
• Expression of a luxS gene is not required for Borrelia burgdorferi infection of mice via needle inoculation [5].

High impact information on luxS

• These results imply a potential cross-communication between the luxS/AI-3 bacterial QS system and the epinephrine host signaling system [6].
• Here we show that an EHEC luxS mutant, unable to produce the bacterial autoinducer, still responds to a eukaryotic cell signal to activate expression of its virulence genes [6].
• Catalytic mechanism of s-ribosylhomocysteinase: ionization state of active-site residues [7].
• S-Ribosylhomocysteinase (LuxS) catalyzes the cleavage of the thioether linkage in S-ribosylhomocysteine (SRH) to produce homocysteine (Hcys) and 4,5-dihydroxy-2,3-pentanedione (DPD), the precursor of type II bacterial autoinducer (AI-2) [7].
• Colonization of gnotobiotic piglets by a luxS mutant strain of Escherichia coli O157:H7 [8].

Chemical compound and disease context of luxS

• Cell-free extracts of Escherichia coli MG1655, but not DH5alpha (which carries a luxS frame-shift mutation) were capable of generating AI-2 activity upon addition of SAH, but not MTA [9].
• Here, we report the adaptation to the E. coli CFAS of a previously reported enzyme-coupled colorimetric assay based on the quantification, using Ellman's reagent, of homocysteine produced from S-adenosyl-L-homocysteine, a product of the reaction, in the presence of AdoHcy nucleosidase and S-ribosylhomocysteinase [10].

Biological context of luxS

• An ortholog of luxS for S. mutans was identified using the data available in the S. mutans genome project (http://www.genome.ou.edu/smutans.html) [11].
• Using an assay developed for the detection of the LuxS-associated quorum sensing signal autoinducer 2 (AI-2), it was demonstrated that this ortholog was able to complement the luxS negative phenotype of Escherichia coli DH5alpha [11].
• The partially annotated genome sequence of Bacillus anthracis contains an open reading frame (BA5047) predicted to encode an ortholog of luxS, required for synthesis of the quorum-sensing signaling molecule autoinducer-2 (AI-2) [4].
• Production of the signaling molecule was restored in an H. pylori luxS null mutant strain by complementation with a single intact copy of luxS placed in a heterologous site on the chromosome [12].
• Consistent with this pattern of gene expression, the luxS mutant grows faster than the wild-type strain (generation times of 37.5 and 60 min, respectively, in Dulbecco modified Eagle medium) [13].

Anatomical context of luxS

• We also observed fewer flagella by Western blotting and electron microscopy and decreased motility halos in semisolid agar in the luxS mutant [13].

Associations of luxS with chemical compounds

• Deletion of luxS was also shown to affect genes involved in methionine biosynthesis, methyl transfer reactions, iron uptake, and utilization of carbon [1].
• Twenty-three genes were affected by luxS deletion in the presence of glucose, and 63 genes were influenced by luxS deletion in the absence of glucose [1].
• The genome sequence of H. pylori 26695 does not contain any gene predicted to encode an acyl homoserine lactone synthase but does contain an orthologue of luxS, which is required for production of autoinducer-2 (AI-2) in V. harveyi [12].
• In contrast, the growth of an DeltayrhA mutant or a luxS mutant, inactivated for the S-ribosyl-homocysteinase step of the S-adenosylmethionine recycling pathway, was strongly reduced with methionine, whereas a DeltayrhA DeltacysK or cysE mutant did not grow at all under the same conditions [14].
• However, in the past 8 years, several research groups have demonstrated that these bacteria use several quorum-sensing systems, such as: the luxS/AI-2, AI-3/epinephrine/norepinephrine, indole, and the LuxR homolog SdiA to achieve intercellular signaling [15].

Analytical, diagnostic and therapeutic context of luxS

• We have identified luxS-controlled genes in Escherichia coli under two different growth conditions using DNA microarrays [1].
• To determine whether quorum sensing plays a role in the regulation of Rgp and Kgp, biosensors capable of detecting either N-acylhomoserine lactone (AHLs) or the luxS-dependent autoinducer (AI-2) quorum-sensing signalling molecules in spent culture supernatants were first employed [16].
• A luxS homolog was cloned by PCR from M. haemolytica A1 using sequencing data from the ongoing genome sequencing project [17].
• A V. harveyi bioassay showed the luxS functionality in K. pneumoniae and its ability to complement the luxS-negative phenotype of Escherichia coli DH5alpha [18].
• Rinses from Roma tomato surfaces that were stored at refrigeration temperature for up to 9 days caused a significant increase (1.8-3.6-fold as compared to the negative controls) in biofilm formation by luxS mutant (non AI-2 producing) generic E. coli and E. coli O157:H7 strains using a micro-titer plate-based biofilm assay [19].

References