lantibiotic-pep5 and epidermin

Lantibiotics are antibiotic peptides that contain the rare thioether amino acids lanthionine and/or methyllanthionine. Epidermin, Pep5 and epilancin K7 are produced by Staphylococcus epidermidis whereas gallidermin (6L-epidermin) was isolated from the closely related species Staphylococcus gallinarum. The biosynthesis of all four lantibiotics proceeds from structural genes which code for prepeptides that are enzymatically modified to give the mature peptides. The genes involved in biosynthesis, processing, export etc. are found in gene clusters adjacent to the structural genes and code for transporters, immunity functions, regulatory proteins and the modification enzymes LanB, LanC and LanD, which catalyze the biosynthesis of the rare amino acids. LanB and LanC are responsible for the dehydration of the serine and threonine residues to give dehydroalanine and dehydrobutyrine and subsequent addition of cysteine SH-groups to the dehydro amino acids which results in the thioether rings. EpiD, the only LanD enzyme known so far, catalyzes the oxidative decarboxylation of the C-terminal cysteine of epidermin which gives the C-terminal S-aminovinylcysteine after addition of a dehydroalanine residue.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; ATP-Binding Cassette Transporters; Bacteriocins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Molecular Sequence Data; Multigene Family; Peptides; Protein Processing, Post-Translational; Staphylococcus; Staphylococcus epidermidis

Whereas protein engineering of enzymes and structural proteins nowadays is an established research tool for studying structure-function relationships of polypeptides and for improving their properties, the engineering of posttranslationally modified peptides, such as the lantibiotics, is just coming of age. The engineering of lantibiotics is less straightforward than that of unmodified proteins, since expression systems should be developed not only for the structural genes but also for the genes encoding the biosynthetic enzymes, immunity protein and regulatory proteins. Moreover, correct posttranslational modification of specific residues could in many cases be a prerequisite for production and secretion of the active lantibiotic, which limits the number of successful mutations one can apply. This paper describes the development of expression systems for the structural lantibiotic genes for nisin A, nisin Z, gallidermin, epidermin and Pep5, and gives examples of recently produced site-directed mutants of these lantibiotics. Characterization of the mutants yielded valuable information on biosynthetic requirements for production. Moreover, regions in the lantibiotics were identified that are of crucial importance for antimicrobial activity. Eventually, this knowledge will lead to the rational design of lantibiotics optimally suited for fighting specific undesirable microorganisms. The mutants are of additional value for studies directed towards the elucidation of the mode of action of lantibiotics.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Bacteriocins; Gene Expression; Genes, Bacterial; Molecular Sequence Data; Mutagenesis, Site-Directed; Nisin; Peptides; Protein Engineering

The production of the lanthionine-containing polypeptide antibiotics gallidermin from Staphylococcus gallinarum TU 3928 and pep 5 from S. epidermidis 5 is investigated with respect to regulation and stimulation of productivity by media components, optimization of both the media used and the fermentation process and is compared to the production of the lantibiotic epidermin from S. epidermidis TU 3298. Efficient methods for rapid quantification of lantibiotics, optimization of the media and a primary enrichment by adsorption chromatography are reported.

Topics: Alanine; Amino Acid Sequence; Anti-Bacterial Agents; Bacteriocins; Chromatography, Gel; Culture Media; Fermentation; Microbial Sensitivity Tests; Molecular Sequence Data; Peptide Biosynthesis; Peptides; Peptides, Cyclic; Staphylococcus; Staphylococcus epidermidis; Sulfides