Structure-Activity Relationships of the S-Linked Glycocin Sublancin.

Sublancin is a 37-amino acid antimicrobial peptide belonging to the glycocin family of natural products. It contains two helices that are held together by two disulfide bonds as well as an unusual S-glucosidic linkage to a Cys in a loop connecting the helices. We report the reconstitution of the biosynthetic pathway to this natural product in Escherichia coli. This technology enabled the evaluation of the structure-activity relationships of the solvent-exposed residues in the helices. The biosynthetic machinery proved tolerant of changes in both helices, and the bioactivity studies of the resulting mutants show that two residues in helix B are important for bioactivity, Asn31 and Arg33.