Cover Picture: Characterization of New Class III Lantibiotics—Erythreapeptin, Avermipeptin and Griseopeptin from Saccharopolyspora erythraea, Streptomyces avermitilis and Streptomyces griseus Demonstrates Stepwise N-Terminal Leader Processing (ChemBioChem 8/2012)

The cover picture shows the structure of the class III lantibiotic LabA2, which displays remarkable antiviral as well as analgesic activities in a neuropathic mouse model. A special feature in its structure is the unusual α,α-disubstituted amino acid labionin. Interestingly LabA2-homologous gene clusters can also be found in a great number of other Actinomycetes such as the model Actinomycete Streptomyces coelicolor and the corresponding ram gene cluster. A MS-based screening led to the discovery of three new representatives of class III lantibiotics and indicated stepwise leader processing by putative aminopeptidase-like protease(s) that yielded mixtures of differently processed lantibiotic peptides. Characterization by HPLC-ESI-MSMS and GC-MS suggests that these lantibiotics are a mixture of peptides, containing both lanthionine and labionin as post-translational modifications. For more information, see the paper by R. D. Süssmuth et al. on p. 1174 ff. The cover picture was prepared by Bichan Maschajechi.