Biosynthesis of the polyene macrolide antibiotic nystatin in Streptomyces noursei

Fjærvik, Espen; Zotchev, Sergey B.

doi:10.1007/s00253-004-1802-4

Cited by 63 publications

(48 citation statements)

References 37 publications

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“…Notably, both the cytochrome P450 NysN and ferredoxin NysM believed to install nystatin's carboxylate at C16 (37) are absent in the selvamicin cluster, consistent with selvamicin's unoxidized methyl substituent at C12. The aminotransferase responsible for ammonium installation on the mycosamine sugar, NysDII, is also absent from the selvamicin cluster.…”

Section: Chemistrymentioning

confidence: 79%

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Selvamicin, an atypical antifungal polyene from two alternative genomic contexts

Arnam

Ruzzini

Sit

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The bacteria harbored by fungus-growing ants produce a variety of small molecules that help maintain a complex multilateral symbiosis. In a survey of antifungal compounds from these bacteria, we discovered selvamicin, an unusual antifungal polyene macrolide, in bacterial isolates from two neighboring ant nests. Selvamicin resembles the clinically important antifungals nystatin A1 and amphotericin B, but it has several distinctive structural features: a noncationic 6-deoxymannose sugar at the canonical glycosylation site and a second sugar, an unusual 4-O-methyldigitoxose, at the opposite end of selvamicin’s shortened polyene macrolide. It also lacks some of the pharmacokinetic liabilities of the clinical agents and appears to have a different target. Whole genome sequencing revealed the putative type I polyketide gene cluster responsible for selvamicin’s biosynthesis including a subcluster of genes consistent with selvamicin’s 4-O-methyldigitoxose sugar. Although the selvamicin biosynthetic cluster is virtually identical in both bacterial producers, in one it is on the chromosome, in the other it is on a plasmid. These alternative genomic contexts illustrate the biosynthetic gene cluster mobility that underlies the diversity and distribution of chemical defenses by the specialized bacteria in this multilateral symbiosis.

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Section: Chemistrymentioning

confidence: 79%

“…The bioinformatically identified selvamicin cluster resembles known type I PKS-derived polyene BGCs (30)(31)(32)(33)(34)(35), and a side-by-side comparison with the well-characterized nystatin BGC (36,37) readily reveals the origins of selvamicin's unusual structural features (Fig. 5).…”

Section: Chemistrymentioning

confidence: 99%

Selvamicin, an atypical antifungal polyene from two alternative genomic contexts

Arnam

Ruzzini

Sit

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…The broad range of biological activities exhibited by macrolides, including antibacterial (35), antifungal (36), and antiproliferative (37) activities, prompted us to investigate the biological activity of the stambomycins. They showed moderate activity against Gram-positive bacteria (SI Appendix, Table S6) but no activity against Gram-negative bac- teria, or fungi.…”

Section: J H-h Coupling Constants Of ∼15 Hz For H-12/h-1and H-48/h-49mentioning

confidence: 99%

Identification of a bioactive 51-membered macrolide complex by activation of a silent polyketide synthase in Streptomyces ambofaciens

Laureti¹,

Song

Huang³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

289

266

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There is a constant need for new and improved drugs to combat infectious diseases, cancer, and other major life-threatening conditions. The recent development of genomics-guided approaches for novel natural product discovery has stimulated renewed interest in the search for natural product-based drugs. Genome sequence analysis of Streptomyces ambofaciens ATCC23877 has revealed numerous secondary metabolite biosynthetic gene clusters, including a giant type I modular polyketide synthase (PKS) gene cluster, which is composed of 25 genes (nine of which encode PKSs) and spans almost 150 kb, making it one of the largest polyketide biosynthetic gene clusters described to date. The metabolic product(s) of this gene cluster are unknown, and transcriptional analyses showed that it is not expressed under laboratory growth conditions. The constitutive expression of a regulatory gene within the cluster, encoding a protein that is similar to Large ATP binding of the LuxR (LAL) family proteins, triggered the expression of the biosynthetic genes. This led to the identification of four 51-membered glycosylated macrolides, named stambomycins A-D as metabolic products of the gene cluster. The structures of these compounds imply several interesting biosynthetic features, including incorporation of unusual extender units into the polyketide chain and in trans hydroxylation of the growing polyketide chain to provide the hydroxyl group for macrolide formation. Interestingly, the stambomycins possess promising antiproliferative activity against human cancer cell lines. Database searches identify genes encoding LAL regulators within numerous cryptic biosynthetic gene clusters in actinomycete genomes, suggesting that constitutive expression of such pathway-specific activators represents a powerful approach for novel bioactive natural product discovery.antibiotic | silent gene cluster | genome mining | structure elucidation | anticancer agent

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“…Postpolyketide modifications of macrolides by cytochrome P450 (P450 or CYP) 2 hydroxylases provide molecular diversity to these macrolides during their biosynthesis (2,3). P450s are hemoproteins whose fifth axial heme iron ligand is a thiolate group found in a variety of organisms (4,5).…”

mentioning

confidence: 99%

“…Analysis of P450 gene deletion mutants revealed that CYP105P1 and CYP105D6 catalyze hydroxylations at posi-tions C26 and C1Ј, respectively. 3 The amino acid sequence identity between CYP105P1 and CYP105D6 is 36.7% when the whole lengths of both sequences are used for alignment.…”

mentioning

confidence: 99%

Regio- and Stereospecificity of Filipin Hydroxylation Sites Revealed by Crystal Structures of Cytochrome P450 105P1 and 105D6 from Streptomyces avermitilis

Fushinobu

Takamatsu

et al. 2010

Journal of Biological Chemistry

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The polyene macrolide antibiotic filipin is widely used as a probe for cholesterol and a diagnostic tool for type C NiemannPick disease. Two position-specific P450 enzymes are involved in the post-polyketide modification of filipin during its biosynthesis, thereby providing molecular diversity to the "filipin complex." CYP105P1 and CYP105D6 from Streptomyces avermitilis, despite their high sequence similarities, catalyze filipin hydroxylation at different positions, C26 and C1, respectively. Here, we determined the crystal structure of the CYP105P1-filipin I complex. The distal pocket of CYP105P1 has the second largest size among P450 hydroxylases that act on macrolide substrates. Compared with previously determined substrate-free structures, the FG helices showed significant closing motion on substrate binding. The long BC loop region adopts a unique extended conformation without a B helix. The binding site is essentially hydrophobic, but numerous water molecules are involved in recognizing the polyol side of the substrate. Therefore, the distal pocket of CYP105P1 provides a specific environment for the large filipin substrate to bind with its pro-S side of position C26 directed toward the heme iron. The ligand-free CYP105D6 structure was also determined. A small sub-pocket accommodating the long alkyl side chain of filipin I was observed in the CYP105P1 structure but was absent in the CYP105D6 structure, indicating that filipin cannot bind to CYP105D6 with a similar orientation due to steric hindrance. This observation can explain the strict regiospecificity of these enzymes.Macrolide compounds have toxic effects on a wide variety of organisms including pathogens, and therefore, their clinical use as antibiotics has been widely developed (1). Postpolyketide modifications of macrolides by cytochrome P450 (P450 or CYP) 2 hydroxylases provide molecular diversity to these macrolides during their biosynthesis (2, 3). P450s are hemoproteins whose fifth axial heme iron ligand is a thiolate group found in a variety of organisms (4, 5). A majority of P450s catalyze monooxygenation (hydroxylation or epoxidation) of hydrophobic substrates (6) using a dioxygen bound as the sixth iron ligand as well as various redox systems responsible for the cleavage of the O-O bond (7-9).Understanding the molecular mechanisms of P450 enzymes during the biosynthesis of natural products would facilitate their potential uses in producing new drugs (10). The crystal structures of macrolide monooxygenases complexed with their substrates or analogues have been determined for P450eryF (CYP107A1; erythromycin biosynthesis) (11, 12), P450 EryK (CYP113A1; erythromycin biosynthesis) (13), P450 PikC (CYP107L1; narbomycin and pikromycin biosynthesis) (14), and P450epoK (CYP167A1; epothilone biosynthesis) (12) (see supplemental Fig. S1). The 28-membered polyene macrolide antibiotic filipin is widely used as a probe for cholesterol in biological membranes (15, 16) and a prominent diagnostic tool for type C Niemann-Pick disease (17, 18). Filipin, origi...

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Biosynthesis of the polyene macrolide antibiotic nystatin in Streptomyces noursei

Cited by 63 publications

References 37 publications

Selvamicin, an atypical antifungal polyene from two alternative genomic contexts

Selvamicin, an atypical antifungal polyene from two alternative genomic contexts

Identification of a bioactive 51-membered macrolide complex by activation of a silent polyketide synthase in Streptomyces ambofaciens

Regio- and Stereospecificity of Filipin Hydroxylation Sites Revealed by Crystal Structures of Cytochrome P450 105P1 and 105D6 from Streptomyces avermitilis

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