Enzymatic C-H Functionalization of l-Arg and l-Leu in Nonribosomally Derived Peptidyl Natural Products: A Tale of Two Oxidoreductases.

Muraymycins are peptidyl nucleoside antibiotics that contain two C-modified amino acids, (2,3)-capreomycidine and (2,3)-β-OH-Leu. The former is also a component of chymostatins, which are aldehyde-containing peptidic protease inhibitors that─like muraymycin─are derived from nonribosomal peptide synthetases (NRPSs). Using feeding experiments and in vitro characterization of 12 recombinant proteins, the biosynthetic mechanism for both nonproteinogenic amino acids is now defined.

Pyridoxal-5'-phosphate-dependent alkyl transfer in nucleoside antibiotic biosynthesis.

Several nucleoside antibiotics are structurally characterized by a 5″-amino-5″-deoxyribose (ADR) appended via a glycosidic bond to a high-carbon sugar nucleoside (5'S,6'S)-5'-C-glycyluridine (GlyU). GlyU is further modified with an N-alkylamine linker, the biosynthetic origin of which has yet to be established. By using a combination of feeding experiments with isotopically labeled precursors and characterization of recombinant proteins from multiple pathways, the biosynthetic mechanism for N-alkylamine installation for ADR-GlyU-containing nucleoside antibiotics has been uncovered.

Enzymatic Synthesis of the Ribosylated Glycyl-Uridine Disaccharide Core of Peptidyl Nucleoside Antibiotics.

Muraymycins belong to a family of nucleoside antibiotics that have a distinctive disaccharide core consisting of 5-amino-5-deoxyribofuranose (ADR) attached to 6'- N-alkyl-5'- C-glycyluridine (GlyU). Here, we functionally assign and characterize six enzymes from the muraymycin biosynthetic pathway involved in the core assembly that starts from uridine monophosphate (UMP). The biosynthesis is initiated by Mur16, a nonheme Fe(II)- and α-ketoglutarate-dependent dioxygenase, followed by four transferase enzymes: Mur17, a pyridoxal-5'-phosphate (PLP)-dependent transaldolase; Mur20, an aminotransferase; Mur26, a pyrimidine phosphorylase; and Mur18, a nucleotidylyltransferase.

Self-Resistance during Muraymycin Biosynthesis: a Complementary Nucleotidyltransferase and Phosphotransferase with Identical Modification Sites and Distinct Temporal Order.

Muraymycins are antibacterial natural products from spp. that inhibit translocase I (MraY), which is involved in cell wall biosynthesis. Structurally, muraymycins consist of a 5'--glycyluridine (GlyU) appended to a 5″-amino-5″-deoxyribose (ADR), forming a disaccharide core that is found in several peptidyl nucleoside inhibitors of MraY.