Covalent structure of mutacin 1140 and a novel method for the rapid identification of lantibiotics

The primary structure of the Streptococcus mutans lantibiotic mutacin 1140 was elucidated by NMR spectroscopy, mass spectrometry, and chemical sequenc ing. The structure is in agreement with other closely related lantibiotics, such as epidermin. A novel method was developed in which mutacin 1140 was chemically modified with sodium borohydride followed by ethanethiol, allowi ng the differentiation of the thioether-containing residues from the dehydr ated residues. This double-labeling strategy provides a simple method to re liably identify all modified lantibiotic residues with a minimal amount of material. While NMR spectroscopy is still required to obtain thioether brid ging patterns and thus the complete covalent structure, the double-labeling technique, along with mass spectrometry, provides most of the information in a fraction of the time required for a complete NMR analysis. Thus, with these new techniques lantibiotics can be rapidly characterized.