PMID:7592489

Citation	Gilson, L, Kuo, A and Dunlap, PV (1995) AinS and a new family of autoinducer synthesis proteins. J. Bacteriol. 177:6946-51
Abstract	In Vibrio fischeri, the autoinducer N-3-oxohexanoyl-L-homoserine lactone (AI-1) governs the cell density-dependent induction of the luminescence operon via the LuxR transcriptional activator. The synthesis of AI-1 from bacterial metabolic intermediates is dependent on luxI. Recently, we found a second V. fischeri autoinducer molecule, N-octanoyl-L-homoserine lactone (AI-2), that in E. coli also activates the luminescence operon via LuxR. A locus independent of luxI was identified as being required for AI-2 synthesis. This 2.7-kb ain (autoinducer) locus was characterized by transposon insertion mutagenesis, deletion and complementation analysis, and DNA sequencing. A single 1,185-bp gene, ainS, was found to be the sole exogenous gene necessary for the synthesis of AI-2 in Escherichia coli. In addition, a V. fischeri ainS mutant produced AI-1 but not AI-2, confirming that in its native species ainS is specific for the synthesis of AI-2. ainS is predicted to encode a 45,580-Da protein which exhibits no similarity to LuxI or to any of the LuxI homologs responsible for the synthesis of N-acyl-L-homoserine lactones in a variety of other bacteria. The existence of two different and unrelated autoinducer synthesis genes suggests the occurrence of convergent evolution in the synthesis of homoserine lactone signaling molecules. The C-terminal half of AinS shows homology to a putative protein in Vibrio harveyi, LuxM, which is required for the synthesis of a V. harveyi bioluminescence autoinducer. Together, AinS and LuxM define a new family of autoinducer synthesis proteins. Furthermore, the predicted product of another gene, ainR, encoded immediately downstream of ainS, shows homology to LuxN, which is similarly encoded downstream of luxM in V. harveyi and proposed to have sensor/regulator functions in the bioluminescence response to the V. harveyi auto inducer. This similarity presents the possibility that AI-2, besides interacting with LuxR, also interacts with AinR under presently unknown conditions.
Links	PubMed PMC177564
Keywords	4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/biosynthesis; Amino Acid Sequence; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Base Sequence; Chromosome Mapping; Escherichia coli/genetics; Escherichia coli/metabolism; Genes, Bacterial; Genetic Complementation Test; Molecular Sequence Data; Mutagenesis, Insertional; Open Reading Frames; Protein Biosynthesis; Regulatory Sequences, Nucleic Acid; Sequence Analysis, DNA; Sequence Deletion; Species Specificity; Vibrio/genetics; Vibrio/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBF1:Q5E614		GO:0016747: transferase activity, transferring acyl groups other than amino-acyl groups	ECO:0000315:		F		Chromosomal mutants of V. fischeri prove show that AinS is required for the synthesis for AI-2.	complete CACAO 9603

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