Required for the synthesis of BHL (N-butanoyl-L-homoserine lactone), and HHL (N-hexanoyl-L-homoserine lactone) autoinducer molecules which bind to RhlR and thus acts in elastase biosynthesis regulation. a fatty acyl-[ACP] + S-adenosyl-L-methionine = an N-acyl-L-homoserine lactone + H(+) + holo-[ACP] + S-methyl-5'-thioadenosine Belongs to the autoinducer synthase family.