LuxI protein

Scheme 2 shows the biosynthesis ofN-(3-oxooctanoyl)-L-homoserine lactone by Tral protein from Agrobacterium using 3-oxooctanoyl-ACP, derived from fatty acid metabolism, as a substrate [29, 33]. Recently, the first crystal structure of a LuxI protein homologue [34] has provided new insights into the function of AHL synthases which will aid the design of novel inhibitors of AHL biosynthesis. 

Although the basic AHL quorum sensing system only consists of two proteins—LuxI and LuxR—a variety of proteins modulates it. These proteins include the AiiA AHL lactonase of Bacillus thuringiensis, which inactivates AHL by hydrolysing... 

LuxI, synthesis from S-adenosyl methionine (SAM) and fatty acid carrier protein no transporter—AHL can diffuse through membranes... 

Figure 2 Representative domain organization and structure of some proteins involved in cell-to-cell communication, (a) The AHL binding transcription factor TraR (b) Esal, a LuxI homologue and involved in AHL synthesis (c) LuxP, a pehplasmic protein binding AI-2 (d) LuxS, a protein involved in AI-2 synthesis (e) the quorum quenching enzyme AiiA.

P. leiognathi (accession number Q06877) LUXP-PHOPO, iumazine protein of Photobacterium phosphoreum (accession number P25082) LUXY-ViBFi, yeiiow fluorescent protein of Vibrio fischeri (accession number P21578) RiSA-SCHPO, riboflavin synthase of S. pombe (accession number Q9Y7P0). identicai amino acid residues are in shadowed typeface. Red boxes indicate amino acid residues in the S. pombe riboflavin synthase structure that contact substrate in the N- or C-terminai domain. The cyiinder represents the C-terminai a-heiix responsibie for trimerization of riboflavin synthases. ... 

Fig. 16.4 Bacterial population control using quorum sensing. Escherichia coli was engineered with luxi and luxR of Vibrio fisheri. In the presence of anhydrotetracycline (aTc), LuxI is expressed and synthesizes the quorum-sensing molecule acyl-homoserine lactone (AHL). The transcriptional regulator LuxR is also expressed and activated by AHL. Then, the AHL-LuxR complex activates and induces the expression of green fluorescent protein (GFP) and the transcriptional repressor CL GFP expression is only activated at low concentrations of AHL at high concentrations Pj j is repressed by CL...

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