Cloning of the gene encoding a novel lantibiotic, nukacin ISK-1, of Staphylococcus warneri

Staphylococcus warneri ISK-1, we had reported as Pediococcus sp. ISK-1 previously, produces a novel bacteriocin, nukacin ISK-1. Edman degradation of the chemically reduced nukacin ISK-1 revealed a sequence of 27 amino acids, 7 of which were unidentified. Using single-specific-primer-PCR (SSP-PCR) product as a probe, a 3.6-kb HindIII fragment containing nukacin ISK-1 structural gene (nukA) was cloned and sequenced. The deduced amino acid sequence of nukacin ISK-1 revealed that it was comprised of 57-amino acids, including a 30-amino acid leader region. The propeptide sequence showed significant similarity to those of lacticin-481 type lantibiotics. It was expected that an active 27-residue nukacin ISK-1 contained two lanthionines, one 3-methyllanthionine, and one dehydrobutyrine. In the region upstream of nukA, a part of long open reading frame (ORF), designated as nukM, encoding a putative modification enzyme involved in the lantibiotic biosynthesis, was oriented in the opposite direction. In the region of downstream of nukA, ORF1 was found, in which the sequence of the putative translational product was similar to those of response regulatory proteins such as LytT of Bacillus subtilis and VirR of Clostridium perfringens.