Purification and structure of mutacin B‐Ny266: a new lantibiotic produced by Streptococcus mutans

Mutacins are bactericidal substances of proteinaceous nature produced by Streptococcus mutans. Lantibiotics are antibacterial substances containing post-translationally modified amino acids such as lanthionine. Mutacin B-Ny266 was purified from the cell pellet of S. mutans strain Ny266 by ethanol extraction at pH 2.0 followed by reversed-phase chromatography (Sep-Pak cartridge) and by HPLC on a C18 column. The mean purification factor was 3240 +/- 81 and the mean yield was 1.0 +/- 0.1%. Molecular mass of mutacin B-Ny266 as determined by mass spectroscopy is 2270.29 +/- 0.21 Da. The amino acid sequence of the purified active fraction was obtained by Edman degradation after treatment with alkaline ethanethiol. Twenty-one amino acids were detected in this analysis. Mutacin B-Ny266 belongs to the type A lantibiotics. The proposed sequence is: F-K-A-W-U-F-A-Abu-P-G-A-A-K-O-G-A-F-N-U-Y-A. The molecule differs from that of epidermin/staphylococcin 1580 and gallidermin at positions 1, 2, 4, 5 and 6.