3oxododecanoylhomoserine

3-oxo-dodecanoyl homoserine lactone, commonly abbreviated 3-oxo-C12-HSL, is an autoinducer molecule used in quorum sensing by Gram-negative bacteria, most notably Pseudomonas aeruginosa. It consists of a homoserine lactone ring attached to a 12-carbon acyl side chain bearing a keto group at the third carbon. The molecule is produced by LasI, a LuxI-family synthase, from S-adenosyl-L-methionine and a long-chain acyl carrier protein donor.

In P. aeruginosa, 3-oxo-C12-HSL diffuses across cell membranes and accumulates as cell density increases. It binds the transcriptional regulator LasR, forming a complex that activates a regulon of virulence and biofilm-associated genes, including elastase (lasB) and components of rhamnolipid synthesis. The signal is part of a hierarchical quorum-sensing network that coordinates multiple communal behaviors and interacts with other signaling systems such as RhlR and PQS.

Beyond its role in bacterial communication, 3-oxo-C12-HSL can influence host cells and interspecies interactions. It has been reported to modulate mammalian immune responses, affecting signaling pathways and cytokine production in some contexts, which can contribute to pathogenicity during infection.

Detection and study of 3-oxo-C12-HSL employ mass spectrometry and biosensor assays, supporting research into quorum-sensing mechanisms and antivirulence strategies. The molecule is relatively hydrophobic and contains a lactone ring that is stable under neutral conditions but can hydrolyze at high pH, leading to loss of signaling activity.