Streptomyces toyocaensis produces A47934, a teicoplanin-like type-IV glycopeptide with antibiotic activity against methicillin-resistant Staphylococcus aureus. A47934 differs from the type-I vancomycin glycopeptides, which possess a tricyclic peptide backbone, by the presence of an additional ring closure between the aromatic amino acids 1 and 3. To elucidate the order of crosslinking reactions, P450 mono-oxygenase-inactivation mutants (DeltastaF, DeltastaG, DeltastaH, and DeltastaJ) of the A47934 producer were generated, and the accumulated intermediates were analyzed. Thus, the formation of each crosslink could unambiguously be assigned to a specific oxygenase. The structure of the released intermediates from the wild-type nonribosomal peptide synthetase assembly line facilitated the determination of the cyclization order. Unexpectedly, the additional ring closure in A47934, catalyzed by StaG, is the second oxygenase reaction.
Don't do it by halves: Genetic engineering of non‐ribosomal peptide synthetases (NRPSs) by module (M) exchange (I) and deletion (II) has previously resulted in amino acid exchange and deletion of the synthesized peptide metabolite. Here we report for the first time the insertion (III) of one complete module into an NRPS assembly line, resulting in an elongated peptide metabolite.
Peptid‐Irrgarten: Die Struktur des neuartigen Lantibiotikums Labyrinthopeptin A2 (siehe Bild) enthält eine zuvor unbekannte carbacyclische, posttranslational modifizierte Aminosäure, die Labionin genannt wurde. Im Anschluss an die Strukturaufklärung gelang die Identifizierung des Biosynthesegenclusters der Labyrinthopeptine. Labyrinthopeptin A2 zeigt eine ausgeprägte In‐vivo‐Wirksamkeit (Verminderung taktiler Allodynie) in der Maus in einem Nervenverletzungsmodell.
Not limited to iron: The high affinity of the bacterial iron siderophores enterobactin and salmochelin for Fe3+ ions, which are bound through chelating catecholate groups, is well known. These two siderophores have now been found to also bind silicon ions with high affinity, giving the first examples of silicon complexes of natural products stable under physiological conditions.
Die hohe Affinität der bakteriellen Eisensiderophore Enterobactin und Salmochelin für Fe3+, das sie über ihre Catecholgruppen als Chelatoren binden, ist wohlbekannt. Nun wurde entdeckt, dass beide Siderophore auch Silicium mit hoher Affinität binden. Dabei entstehen die ersten bekannten Siliciumkomplexe von Naturstoffen, die unter physiologischen Bedingungen stabil sind. Untersuchungen der isolierten Siliciumkomplexe deuten zudem an, dass darin SiIV in sechsfach koordiniertem Zustand vorliegt (siehe Bild).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.