The LcnC homologue cannot replace LctT in lacticin 481 export

Lacticin 481 is produced by Lactococcus lactis subsp. lactis and belongs to subgroup AII of the lanthionine-containing bacteriocins. The putative homodimeric LctT involved in lacticin 481 production shares significant similarities with the ‘LcnC’ protein encoded by ‘lcnC’, located on the chromosome of the lactic acid bacterium, L. lactis IL1403. LctT and ‘LcnC’ belong to the recently defined family of AMS (ABC transporter maturation and secretion) proteins. Inactivation of the ‘lcnC’ gene demonstrates that it is not responsible for the weak lacticin 481 production observed in a strain expressing only the precursor peptide LctA, and the modification enzyme LctM. This result indicates that the two AMS proteins, ‘LcnC’ and LctT, are not interchangeable in the machinery of processing/export of lacticin 481.