Analysis of the Genetic Determinant for Production of the Peptide Antibiotic Nisin

Abstract

The structural gene for the precursor of the peptide antibiotic nisin was isolated and characterized. As with other Ianthionine-contahincontaining antibiotics, din is synthesized as a pre-propeptide which undergoes post-translational modification to generate the mature antibiotic. The sequence data obtained agreed with those of precursor nish genes isolated by other workers from different Lactococcus Zactis strains. Analysis of regions flanking the precursor &in gene revealed the presence of a downstream open reading frame that may be involved in maturation of the precursor molecule. Nucleotide sequences characteristic of an IS element were located upstream of the nisin determinant. This element, termed IS904, is present in multiple copies in the genome of L Zactis. The nisin determinant of L. lactis is a component of a large transmissible gene block that also encodes nisin resistance and sucrose-metabolizing genes. Gene probe experiments indicated that the nisin/sucrose gene block was located in the chromosome. Furthermore, the copy of IS904 identified adjacent to the precursor nisin gene lies at, or very close to, one end of this transmissible DNA segment and may play a roR in mediating its transfer between strains.