FIG. 1.

Autoregulation of nisin biosynthesis and immunity in nisin-producing L. lactis strains. The nisin precursor is posttranslationally modified and secreted by the biosynthetic NisBCTP machinery, and the producer strain is protected from the antimicrobial activity of nisin by the immunity proteins NisIFEG. When confronted with nisin, the transmembrane histidine kinase NisK autophosphorylates and subsequently transfers the phosphate to NisR. The phosphorylated NisR binds to the nisA and nisF promoters, thereby activating transcription of the genes downstream from the promoters.