Photocollection

Lantibiotic biosynthesis

A Lantibiotics such as epidermin, nisin, Pep5, and subtilin are ribosomally synthesized as prepeptides and post-translationally converted into the mature peptide [reviewed in (1)]. They are characterized by the occurrence of the thioether amino acids (2S, 6R)-meso-lanthionine and (2S, 3S, 6R)-3-methyllanthionine. In addition to the thioether amino acids, other unusual amino acids such as didehydroalanine, didehydrobutyrine, and D-alanine are present in some of the lantibiotics. In contrast to the similar lantibiotics nisin and Pep5, epidermin contains the structural element S-[(Z)-2-aminovinyl]-D-cysteine at the C-terminus. Proposed modification reactions involved in lantibiotic biosynthesis are dehydration of serine and threonine residues and sulfide-bridge formation.
Epidermin is synthesized as the 52-amino-acid prepeptide EpiA (N-terminal leader peptide with amino acids -30 to -1 and C-terminal proepidermin with amino acids +1 to +22), which is post-translationally modified and processed to the mature tetracyclic 22-amino-acid peptide antibiotic, as elucidated by sequencing the structural gene epiA (2). EpiA is flanked by epiB, epiC, and epiD, whose gene products are involved in modification of the prepeptide EpiA (3, 4). Two additional genes, epiQ and epiP, are encoded in the opposite direction downstream of epiD. EpiQ controls epidermin production by transcriptionally activating the epiA promoter, used for transcription of most of the epidermin biosynthetic genes (5). With the plasmid pTepi14 con-taining the two transcription units epiABCD and epiPQ, the heterologous host Staphylococcus carnosus synthesizes epidermin (3).
Presently, we are investigating the function of the enzymes EpiB, EpiC, EpiD, and EpiP in epidermin biosynthesis. epiD encodes a flavoprotein (6) that catalyzes the oxidative decarboxylation of the C-terminal cysteine residue of precursor peptide EpiA (7-9) and consequently is involved in formation of the modified C-terminus of epidermin. The final modification step in lantibiotic biosynthesis is the removal of the leader peptide catalyzed by serine protease EpiP (10).

Selected references:

  1. Sahl, H.-G., R. W. Jack, and G. Bierbaum. 1995. Biosynthesis and biological activities of lantibiotics with unique post-translational modifications. Eur. J. Biochem. 230:827-853.
  2. Schnell, N., K.-D. Entian, U. Schneider, F. Götz, H. Zähner, R. Kellner, and G. Jung. 1988. Prepeptide sequence of epidermin, a ribosomally synthesized antibiotic with four sulphide-rings. Nature. 333:276-278.
  3. Augustin, J., R. Rosenstein, B. Wieland, U. Schneider, N. Schnell, G. Engelke, K.-D. Entian, and F. Götz. 1992. Genetic analysis of epidermin biosynthetic genes and epidermin-negative mutants of Staphylococcus epidermidis. Eur. J. Biochem. 204:1149-1154.
  4. Schnell, N., G. Engelke, J. Augustin, R. Rosenstein, V. Ungermann, F. Götz, and K.-D. Entian. 1992. Analysis of genes involved in the biosynthesis of lantibiotic epidermin. Eur. J. Biochem. 204:57-68.
  5. Peschel, A., J. Augustin, T. Kupke, S. Stevanovic, and F. Götz. 1993. Regulation of epidermin biosynthetic genes by EpiQ. Mol. Microbiol. 9:31-39.
  6. Kupke, T., S. Stevanovic, H.-G. Sahl, and F. Götz. 1992. Purification and characterization of EpiD, a flavoprotein involved in the biosynthesis of the lantibiotic epidermin. J. Bacteriol. 174:5354-5361.
  7. Kupke, T., C. Kempter, V. Gnau, G. Jung, and F. Götz. 1994. Mass spectroscopic analysis of a novel enzymatic reaction: oxidative decarboxylation of the lantibiotic precursor peptide EpiA catalyzed by the flavoprotein EpiD. J. Biol. Chem. 269:5653-5659.
  8. Kupke, T., C. Kempter, G. Jung, and F. Götz. 1995. Oxidative decarboxylation of peptides catalyzed by flavoprotein EpiD: determination of substrate specificity using peptide libraries and neutral loss mass spectrometry. J. Biol. Chem. 270:11282-11289.
  9. Kupke, T., and F. Götz. 1997. The enethiolate anion reaction products of EpiD:
    pKa value of the enethiol side chain is lower than that of the thiol side chain of peptides. J. Biol. Chem. 272:4759-4762.
  10. Geißler, S., F. Götz, and T. Kupke. 1996. Serine-protease EpiP from Staphylococcus epidermidis catalyzes the processing of the epidermin precursor peptide. J. Bacteriol. 178(1):284-288.