Homoserine Lactones

N-acyl homoserine lactones (AHLs) are a class of small signal molecules called autoinducers which coordinate gene expression based on cell density in gram-negative bacteria. This system is called quorum sensing. AHLs consist of a fatty acid coupled to a homoserine lactone (HSL). The molecules differ in functional group substitution (hydrogen, hydroxy or oxo group) at the third carbon of the chain (C3) and in chain length (typically C4 – C18) giving signal specificity.