N-butanoyl-L-homoserine lactone (C4-HSL) is a signaling molecule involved in quorum sensing in certain Gram-negative bacteria, particularly Pseudomonas species. C4-HSL is synthesized through a pathway that begins with the precursor L-homoserine. The enzyme ButM, which is part of the N-acylhomoserine lactone (AHL) synthase family, catalyzes the conversion of L-homoserine into N-butanoyl-L-homoserine lactone by attaching a butanoyl group to the amino group of homoserine. This reaction requires butyryl-CoA as the donor of the butanoyl group, facilitating the production of C4-HSL. C4-HSL is secreted by the bacteria and can accumulate in the extracellular environment as the population density increases. Once a threshold concentration of C4-HSL is reached, it binds to specific transcriptional regulators like LasR in Pseudomonas aeruginosa, activating the expression of genes involved in biofilm formation, virulence, and antibiotic resistance. The biosynthesis of C4-HSL is an essential component of bacterial communication, allowing the bacteria to coordinate collective behaviors and adapt to changing environmental conditions. This pathway exemplifies how bacteria use small molecules like C4-HSL to regulate gene expression and engage in cooperative actions that enhance their survival and pathogenicity.

Quorum sensing: N-butanoyl-L-homoserine lactone (C4-HSL) Biosynthesis References