PMID:8790360

Citation	Schaefer, AL, Val, DL, Hanzelka, BL, Cronan, JE Jr and Greenberg, EP (1996) Generation of cell-to-cell signals in quorum sensing: acyl homoserine lactone synthase activity of a purified Vibrio fischeri LuxI protein. Proc. Natl. Acad. Sci. U.S.A. 93:9505-9
Abstract	Many bacteria use acyl homoserine lactone signals to monitor cell density in a type of gene regulation termed quorum sensing and response. Synthesis of these signals is directed by homologs of the luxi gene of Vibrio fischeri. This communication resolves two critical issues concerning the synthesis of the V. fischeri signal. (i) The luxI product is directly involved in signal synthesis-the protein is an acyl homoserine lactone synthase; and (ii) the substrates for acyl homoserine lactone synthesis are not amino acids from biosynthetic pathways or fatty acid degradation products, but rather they are S-adenosylmethionine (SAM) and an acylated acyl carrier protein (ACP) from the fatty acid biosynthesis pathway. We purified a maltose binding protein-LuxI fusion polypeptide and showed that, when provided with the appropriate substrates, it catalyzes the synthesis of an acyl homoserine lactone. In V. fischeri, luxi directs the synthesis of N-(3-oxohexanoyl) homoserine lactone and hexanoyl homoserine lactone. The purified maltose binding protein-LuxI fusion protein catalyzes the synthesis of hexanoyl homoserine lactone from hexanoyl-ACP and SAM. There is a high level of specificity for hexanoyl-ACP over ACPs with differing acyl group lengths, and hexanoyl homoserine lactone was not synthesized when SAM was replaced with other amino acids, such as methionine, S-adenosylhomocysteine, homoserine, or homoserine lactone, or when hexanoyl-SAM was provided as the substrate. This provides direct evidence that the LuxI protein is an auto-inducer synthase that catalyzes the formation of an amide bond between SAM and a fatty acyl-ACP and then catalyzes the formation of the acyl homoserine lactone from the acyl-SAM intermediate.
Links	PubMed PMC38458
Keywords	4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/biosynthesis; ATP-Binding Cassette Transporters; Acyl Carrier Protein/metabolism; Bacterial Proteins/metabolism; Blotting, Western; Carbon-Sulfur Ligases; Carrier Proteins/metabolism; Chromatography, High Pressure Liquid; Escherichia coli/metabolism; Escherichia coli Proteins; Gene Expression Regulation, Enzymologic; Hydrogen-Ion Concentration; Kinetics; Ligases/metabolism; Maltose-Binding Proteins; Monosaccharide Transport Proteins; Plasmids/metabolism; Recombinant Fusion Proteins/metabolism; S-Adenosylmethionine/metabolism; Signal Transduction; Temperature; Transcription Factors/metabolism; Vibrio/enzymology; Vibrio/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ALIFS:Q6WEL3		GO:1901336: lactone biosynthetic process	ECO:0000314:		P		Table 1	complete CACAO 8688
ALIFS:Q6WEL3	involved_in	GO:1901336: lactone biosynthetic process	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

References

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