New Paper by the Piel Lab

Enzyme from an uncultivated sponge bacterium catalyzes S-methylation in a ribosomal peptide.

by Markus Christian Schlumberger

Maximilian J. Helf, Aurelia Jud and Jörn Piel.

Chembiochem. 2016 Dec 14. doi: 10.1002/cbic.201600594.

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Amino  acid modifications  are  essential for the  structural diversity  and  bioactivity  of  ribosomally  synthesized  and posttranslationally  modified  peptide  natural  products  (RiPPs).  A particularly large and virtually untapped pool of unusual RiPPs and associated modifying enzymes is provided by uncultivated bacteria. An  example  is  the  chemically  rich  sponge  symbiont  'Candidatus Entotheonella  factor’  that  produces  the  hypermodified polytheonamides  of  the  poorly  studied  proteusin  RiPP  family.  In addition  to  the  polytheonamide  genes,  'E.  factor'  contains  several further additional RiPP clusters of unknown function. Here we provide insights into one of the cryptic proteusin pathways by identifying an enzyme (PtyS) that catalyzes the S-methylation of cysteine residues. S-methylcysteine  is  rare  in  natural  peptides  and  proteins  and  the enzymatic activity was previously unknown for RiPPs, thus adding a new modification to the ribosomal peptide toolbox.

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