Browsing by Author "Elsayed, S.S."
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Item Biosynthesis of Neocarazostatin A Reveals the Sequential Carbazole Prenylation and Hydroxylation in the Tailoring Steps(Chemistry & Biology, 2015-12) Huang, S.; Elsayed, S.S.; Lv, M.; Tabudravu, J.; Rateb, E.M.; Gyampoh, R.; Kyeremeh, K.; Ebel, R.; Jaspars, M.; Deng, Z.; Yu, YI.; Deng, H.Neocarazostatin A (NZS) is a bacterial alkaloid with promising bioactivities against free radicals, featuring a tricyclic carbazole nucleus with a prenyl moiety at C-6 of the carbazole ring. Here, we report the discovery and characterization of the biosynthetic pathway of NZS through genome mining and gene inactivation. The in vitro assays characterized two enzymes: NzsA is a P450 hydroxylase and NzsG is a new phytoene-synthase-like prenyltransferase (PTase). This is the first reported native PTase that specifically acts on the carbazole nucleus. Finally, our in vitro reconstituted experiment demonstrated a coupled reaction catalyzed by NzsG and NzsA tailoring the NZS biosynthesis.Item Discovery of a Single Monooxygenase that Catalyzes Carbamate Formation and Ring Contraction in the Biosynthesis of the Legonmycins.(Angewandte Chemie International Edition, 2015-07) Huang, S.; Tabudravu, J.; Elsayed, S.S.; Travert, J.; Peace, D.; Tong, M.H.; Kyeremeh, K.; Kelly, S.M.; Trembleau, L.; Ebel, R.; Jaspars, M.; Yu, Y.; Deng, H.Pyrrolizidine alkaloids (PAs) are a group of natural products with important biological activities. The discovery and characterization of the multifunctional FAD‐dependent enzyme LgnC is now described. The enzyme is shown to convert indolizidine intermediates into pyrrolizidines through an unusual ring expansion/contraction mechanism, and catalyze the biosynthesis of new bacterial PAs, the so‐called legonmycins. By genome‐driven analysis, heterologous expression, and gene inactivation, the legonmycins were also shown to originate from non‐ribosomal peptide synthetases (NRPSs). The biosynthetic origin of bacterial PAs has thus been disclosed for the first time.