The third member of the nisin variant, nisin Q, produced by Lactococcus lactis 61-14, is a ribosomally-synthesized antimicrobial peptide, the so-called lantibiotic containing post-translationally modified amino acids such as lanthionine and dehydroalanine. Here, we determined the complete covalent structure of nisin Q, consisting of 34 amino acids, by two-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy. Sequential assignment of nisin Q containing the unusual amino acids was performed by total correlation spectroscopy (TOCSY) and nuclear Overhauser enhancement spectroscopy (NOESY). The observed long range nuclear Overhauser effect (NOE) in nisin Q indicated assignment of all five sets of lanthionines that intramolecularly bridge residues 3-7, 8-11, 13-19, 23-26, and 25-28. Consequently, the covalent structure of nisin Q was determined to hold the same thioether linkage formation as the other two nisins, but to harbor the four amino acid substitutions, in contrast with nisin A.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Applied Microbiology and Biotechnology
- Molecular Biology
- Organic Chemistry