NisT, the Transporter of the Lantibiotic Nisin, Can Transport Fully Modified, Dehydrated, and Unmodified Prenisin and Fusions of the

Lantibiotics are lanthionine-containing peptide anti-biotics. Nisin, encoded by nisA, is a pentacyclic lantibi-otic produced by some Lactococcus lactis strains. Its thioether rings are posttranslationally introduced by a membrane-bound enzyme complex. This complex is composed of three enzymes: NisB, which dehydrates serines and threonines; NisC, which couples these dehy-drated residues to cysteines, thus forming thioether rings; and the transporter NisT. We followed the activity of various combinations of the nisin enzymes by meas-uring export of secreted peptides using antibodies against the leader peptide and mass spectroscopy for detection. L. lactis expressing the nisABTC genes effi-ciently produced fully posttranslationally modified pre-nisin. Strikingly, L. lactis expressing the nisBT gene