N-octanoyl-L-homoserine lactone (C8-HSL) is a quorum sensing signaling molecule produced by some Gram-negative bacteria, such as Vibrio species, which use it to regulate collective behaviors like biofilm formation, virulence, and motility. The biosynthesis of C8-HSL is catalyzed by acyl-homoserine lactone (AHL) synthase enzymes, typically belonging to the LuxI family. The biosynthetic process starts with L-homoserine, which serves as the core structure of the molecule. The enzyme then attaches an octanoyl group derived from octanoyl-CoA to the amino group of L-homoserine, forming an amide bond. This intermediate is then cyclized to form N-octanoyl-L-homoserine lactone (C8-HSL). Additionally, during this process, N-(3-oxooctanoyl)-L-homoserine lactone (3-oxo-C8-HSL) can also be produced, which incorporates a keto group at the third carbon of the acyl chain. This modification is carried out by specific LuxI-family homologs that catalyze the addition of the 3-oxo group during the attachment of the acyl chain. Both C8-HSL and 3-oxo-C8-HSL are quorum sensing molecules that diffuse into the extracellular environment, with their concentration increasing as the bacterial population density rises. When these signaling molecules reach a critical threshold, they bind to specific transcriptional regulators, such as LasR or other LuxR-family receptors. The binding of C8-HSL or 3-oxo-C8-HSL to these receptors triggers the activation of quorum sensing-regulated genes, allowing the bacteria to coordinate group behaviors. This system enables bacteria to adapt to their environment, enhancing their survival and pathogenicity by synchronizing actions that require collective effort, such as the expression of virulence factors or the formation of biofilms.

Quorum sensing: N-Octanoyl-L-homoserine lactone (C8-HSL) and N-(3-Oxooctanoyl)-L-homoserine lactone Biosynthesis References