posted on 2016-02-20, 19:03authored byBartlomiej Krawczyk, Paul Ensle, Wolfgang
M. Müller, Roderich D. Süssmuth
The biosynthesis of a considerable number of ribosomally
synthesized
peptide antibiotics involves the modification of Ser and Thr residues
of a precursor peptide. This post-translational processing is performed
by one or multiple modifying enzymes encoded in the biosynthetic gene
cluster. We present a deuterium-label based enzyme assay, utilizing
a series of peptide substrates with α-deuterated Ser, for the
determination of the dehydration order during the biosynthesis of
class III lantibiotic labyrinthopeptin A2. Remarkably, the data show
that, in contrast to other modifying enzymes of class I and II lantibiotics,
LabKC has a C- to N-terminal processing mode. This surprising finding,
which we consider relevant for the biosyntheses of other class III
lantibiotics, underlines significant differences of this class of
modifying enzymes compared to other investigated systems.