Core Assembly Mechanism of Quinocarcin/SF-1739: Bimodular Complex Nonribosomal Peptide Synthetases for Sequential Mannich-type Reactions

Abstract

Quinocarcin and SF-1739, potent antitumor antibiotics, share a common tetracyclic tetrahydroisoquinoline (THIQ)-pyrrolidine core scaffold. Herein, we describe the identification of their biosynthetic gene clusters and biochemical analysis of Qcn18/Cya18 generating the previously unidentified extender unit dehydroarginine, which is a component of the pyrrolidine ring. ATP-inorganic pyrophosphate exchange experiments with five nonribosomal peptide synthetases (NRPSs) enabled us to identify their substrates. On the basis of these data, we propose that a biosynthetic pathway comprising a three-component NRPS/MbtH family protein complex, Qcn16/17/19, plays a key role in the construction of tetracyclic THIQ-pyrrolidine core scaffold involving sequential Pictet-Spengler and intramolecular Mannich reactions. Furthermore, data derived from gene inactivation experiments led us to propose late-modification steps of quinocarcin.

Identification and analysis of the bacterial endosymbiont specialized for production of the chemotherapeutic natural product ET‐743

“…We previously identified a 35 kb contig containing many of the genes involved in the biosynthesis of the chemotherapeutic natural product ET‐743 (Rath et al ., ). However, close examination of ET‐743, its previously isolated precursors (Rinehart et al ., ) and other well‐studied tetrahydroisoquinoline natural products (Pospiech et al ., ; Velasco et al ., ; Lei et al ., ; Hiratsuka et al ., ) led us to suspect that we were still missing a number of key biosynthetic genes (Rath et al ., ). Expanding the 35 kb gene cluster to a complete genome for Ca .…”

“…The enzyme complex can work with an acyl carrier protein (ACP) to provide a glycolicacyl‐S‐ACP extender unit ( 5 ) for a non‐ribosomal peptide synthetase (NRPS). Both of these gene clusters in addition to SF‐1739 (Hiratsuka et al ., ) and the original ET‐743 (Rath et al ., ) biosynthetic gene cluster contain the E1 and E2 components for the enzyme complex. Although the E3 component has been absent in previously studied clusters, purified exogenous E3 does seem necessary for complete product conversion (Peng et al ., ).…”

The Pictet-Spengler Reaction Updates Its Habits

“…(2013) The Oikawa group reported then the identification of the biosynthetic gene clusters of quinocarcin and the antitumor antibiotic SF-1739, which share a common type II tetracyclic tetrahydroisoquinoline (THIQ)-pyrrolidine core scaffold. The authors proposed a reaction pathway for the construction of the quinocarcin core scaffold (sketched in Scheme 75), with similar protagonists as for saframycin and involving one P-S and one intramolecular Mannich reaction [249].…”

“…(2013) The Oikawa group reported then the identification of the biosynthetic gene clusters of quinocarcin and the antitumor antibiotic SF-1739, which share a common type II tetracyclic tetrahydroisoquinoline (THIQ)-pyrrolidine core scaffold. The authors proposed a reaction pathway for the construction of the quinocarcin core scaffold (sketched in Scheme 75), with similar protagonists as for saframycin and involving one P-S and one intramolecular Mannich reaction [249]. Ju and coworkers identified three genes mcbA, mcbB, and mcbC as the solely responsible for scaffold construction of marinacarbolines (MCBs), 1-acetyl-β-carboline (255a), and 1-acetyl-3carboxy-β-carboline (255b), which were isolated from Marinactispora thermotolerans.…”

The incorporation and removal of ″auxiliary″ building blocks and their functions in the biosynthesis of polyketides and non-ribosomal polypeptides

“…在萘啶霉素(naphthyridinomycin, NDM)和喹诺卡星 (quinocarcin, QCN)生物合成中被发现 [28,29] . 然而, 在 番红霉素 A(Saframycin A, SFM A)中却只缺失脂肪 酸单元 [30] .…”