Required for the synthesis of OHHL (N-(3-oxohexanoyl)-L-homoserine lactone), an autoinducer molecule which binds to ExpR and thus acts in virulence (soft rot disease) through the activation of genes for plant tissue macerating enzymes. 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.