echinomycin and quinomycin

Mangrove actinomycetia have been proven to be one of the promising sources for discovering novel bioactive natural products. Quinomycins K (

Topics: Anti-Bacterial Agents; Echinomycin; Magnetic Resonance Spectroscopy; Molecular Structure; Streptomyces

Two novel quinomycins I (1) and J (3) were discovered by UPLC-MS, then the two novel compounds and five known quinomycins A(2), B(4), E(5), C(6) and monosulfoxide quinomycin (7) were isolated from the culture broth of Streptomyces sp. HCCB11876. The structures of these compounds were elucidated through MS and NMR spectroscopic analysis. Compounds 1-7 showed significant antibacterial and cytotoxic activities. The structure-activity relationship indicated that sulfoxide group in N-methylcysteine of quinomycins (1, 3 and 7) would significantly decrease the antibacterial and cytotoxic activities. Moreover, the antibacterial and cytotoxic activities were decreased with the increase of carbon chain in amino-acid residues.

Topics: Anti-Bacterial Agents; Antineoplastic Agents; Chromatography, High Pressure Liquid; Culture Media; Echinomycin; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Streptomyces; Structure-Activity Relationship

Tuberculosis is an infectious disease of global concern. Members of the diazaquinomycin (DAQ) class of natural products have shown potent and selective activity against drug-resistant Mycobacterium tuberculosis. However, poor solubility has prevented further development of this compound class. Understanding DAQ biosynthesis may provide a viable route for the generation of derivatives with improved properties. We have sequenced the genomes of two actinomycete bacteria that produce distinct DAQ derivatives. While software tools for automated biosynthetic gene cluster (BGC) prediction failed to detect DAQ BGCs, comparative genomics using MAUVE alignment led to the identification of putative BGCs in the marine Streptomyces sp. F001 and in the freshwater Micromonospora sp. B006. Deletion of the identified daq BGC in strain B006 using CRISPR-Cas9 genome editing abolished DAQ production, providing experimental evidence for BGC assignment. A complete model for DAQ biosynthesis is proposed based on the genes identified. Insufficient knowledge of natural product biosynthesis is one of the major challenges of productive genome mining approaches. The results reported here fill a gap in knowledge regarding the genetic basis for the biosynthesis of DAQ antibiotics. Moreover, identification of the daq BGC shall enable future generations of improved derivatives using biosynthetic methods.

Topics: Actinobacteria; Clustered Regularly Interspaced Short Palindromic Repeats; Echinomycin; Fresh Water; Gene Deletion; Genes, Bacterial; Multigene Family; Seawater

Two new cytotoxic antibiotics designated quinomycins H1 (2) and H2 (3) were isolated from the culture broth of Streptomyces sp. RAL404. The molecular formula of both compounds was established as C

Topics: Animals; Cell Line; Echinomycin; Fibroblasts; Molecular Structure; Neuroglia; Rats; Streptomyces; Structure-Activity Relationship

Quinomycin G (1), a new analogue of echinomycin, together with a new cyclic dipeptide, cyclo-(l-Pro-4-OH-l-Leu) (2), as well as three known antibiotic compounds tirandamycin A (3), tirandamycin B (4) and staurosporine (5), were isolated from Streptomyces sp. LS298 obtained from a marine sponge Gelliodes carnosa. The planar and absolute configurations of compounds 1 and 2 were established by MS, NMR spectral data analysis and Marfey's method. Furthermore, the differences in NMR data of keto-enol tautomers in tirandamycins were discussed for the first time. Antibacterial and anti-tumor activities of compound 1 were measured against 15 drug-sensitive/resistant strains and 12 tumor cell lines. Compound 1 exhibited moderate antibacterial activities against Staphylococcuse pidermidis, S. aureus, Enterococcus faecium, and E. faecalis with the minimum inhibitory concentration (MIC) values ranged from 16 to 64 μg/mL. Moreover, it displayed remarkable anti-tumor activities; the highest activity was observed against the Jurkat cell line (human T-cell leukemia) with an IC50 value of 0.414 μM.

Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Bacteria; Cell Line, Tumor; Dipeptides; Drug Resistance, Bacterial; Echinomycin; Humans; Inhibitory Concentration 50; Jurkat Cells; Magnetic Resonance Spectroscopy; Mass Spectrometry; Microbial Sensitivity Tests; Porifera; Streptomyces

Quinomycin antibiotics, represented by echinomycin, are an important class of antitumor antibiotics. We have recently succeeded in identification of biosynthetic gene clusters of echinomycin and SW-163D, and have achieved heterologous production of echinomycin in Escherichia coli. In addition, we have engineered echinomycin non-ribosomal peptide synthetase to generate echinomycin derivatives. However, the biosynthetic pathways of intercalative chromophores quinoxaline-2-carboxylic acid (QXC) and 3-hydroxyquinaldic acid (HQA), which are important for biological activity, were not fully elucidated. Here, we report experiments involving incorporation of a putative advanced precursor, (2S, 3R)-[6'-(2)H]-3-hydroxy-L-kynurenine, and functional analysis of the enzymes Swb1 and Swb2 responsible for late-stage biosynthesis of HQA. On the basis of these experimental results, we propose biosynthetic pathways for both QXC and HQA through the common intermediate 3-hydroxy-L-kynurenine.

Topics: Antibiotics, Antineoplastic; Cloning, Molecular; DNA, Bacterial; Echinomycin; Escherichia coli; Genes, Bacterial; Kynurenic Acid; Kynurenine; Magnetic Resonance Spectroscopy; Multigene Family; Optical Rotation; Peptide Synthases; Polymerase Chain Reaction; Quinoxalines; Spectrometry, Mass, Electrospray Ionization

Topics: Biological Factors; Depsipeptides; Echinomycin; Escherichia coli; Genetic Engineering; Methyltransferases; Molecular Conformation

SW-163C and E are novel antitumor antibiotics, which belong to quinomycin family, isolated from the culture broth of Streptomyces sp. SNA15896. These compounds were determined to be cyclic depsipeptides having 3-hydroxyquinaldic acid as a chromophore and a sulfur-containing intramolecular cross linkage through various spectroscopic analyses.

Topics: Antibiotics, Antineoplastic; Chemical Phenomena; Chemistry, Physical; Depsipeptides; Echinomycin; Magnetic Resonance Spectroscopy; Molecular Structure; Molecular Weight; Peptides, Cyclic; Spectrometry, Mass, Fast Atom Bombardment; Spectrophotometry; Streptomyces; Sulfur

Synthesized 5-arylamino-2-methyl-4,7-dioxobenzothiazoles 3a-3o were evaluated for modulation of NAD(P)H: quinone oxidoreductase (NQO1) activity with the cytosolic fractions derived from cultured human lung cancer cells and their cytotoxicity in cultured several human solid cancer cell lines. The 4,7-dioxobenzothiazoles affected the reduction potential by NQO1 activity and showed a potent cytotoxic activity against human cancer cell lines. The tested compounds 3a, 3b, 3g, 3h, 3n and 3o were considered as more potent cytotoxic agents, and comparable modulators of NQO1 activity.

Topics: Antineoplastic Agents; Drug Screening Assays, Antitumor; Echinomycin; Enzyme Inhibitors; Humans; NAD(P)H Dehydrogenase (Quinone); Quinone Reductases; Thiazoles; Tumor Cells, Cultured

The quinomycin antibiotic UK-63052 (designated QN) exhibits a chemical structure related to the antibiotic echinomycin which is known to bisintercalate into DNA. Common features among these antibiotics include two heterocyclic aromatic ring systems propagating from a cross-bridged cyclic octadepsipeptide scaffold. We report on the solution structure of the QN-d(A1-C2-A3-C4-G5-T6-G7-T8) complex (one QN molecule per duplex) based on a combined NMR-molecular dynamics study including intensity-based refinement. The 3-hydroxy quinaldic acid rings bisintercalate into the duplex at (A3-C4).(G5-T6) steps and stack with flanking Watson-Crick A3.T6 and C4.G5 base-pairs. The intercalation sites at (A3-C4).(G5-T6) steps are wedge-shaped and unwound, with significant unwinding also observed at the (C4-C5).(C4-G5) step bracketed between the intercalation sites. The cross-bridged cyclic octadepsipeptide is positioned in the minor groove with the methyl groups on its Ala and NMe-MCp residues directed towards and making van der Waals contacts with the minor groove edge of the duplex. A pair of adjacent intermolecular hydrogen bonds between the Ala backbone atoms and the G5 minor groove edge (Ala-NH to G5-N(3) and G5-NH2e to Ala-CO) account for the sequence specificity associated with complex formation. The solution structure of the QN-DNA oligomer complex, which contains only Watson-Crick base-pairs flanking the bisintercalation site, is compared with the crystal structure of the related echinomycin-DNA oligomer complex, which contains Hoogsteen base-pairs on either side of the bisintercalation site.

Topics: Anti-Bacterial Agents; Binding Sites; Computer Graphics; DNA; Echinomycin; Hydrogen Bonding; Intercalating Agents; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Nucleic Acid Conformation; Oligodeoxyribonucleotides; Protons; Solubility

Phorbol dibutyrate induced a nitroblue tetrazolium-reducing reaction in differentiated HL-60 cells, which was inhibited by protein kinase inhibitors such as staurosporine and H-7. ID50 of staurosporine and H-7 were 1.4 ng/ml and 0.19 mM, respectively. When tautomycin, an inhibitor of protein phosphatases, was added with the kinase inhibitors, the nitroblue tetrazolium-reducing reaction again appeared. ID50 of staurosporine was 510 ng/ml in the presence of tautomycin. Tautomycin itself weakly induced the reaction, which was inhibited by kinase inhibitors. Such a competitive effect between tautomycin and staurosporine was not observed in a cell-free system of protein kinase C. Okadaic acid had the same effect as tautomycin. The similar results were obtained when respiratory burst was quantitated by measuring H2O2 produced by canine peripheral neutrophils. The mechanism of competitive effect of tautomycin and staurosporine on respiratory burst is discussed.

Topics: Alkaloids; Animals; Antifungal Agents; Cells, Cultured; Dogs; Echinomycin; Ethers, Cyclic; Hydrogen Peroxide; Nitroblue Tetrazolium; Okadaic Acid; Phorbol 12,13-Dibutyrate; Pyrans; Respiratory Burst; Spiro Compounds; Staurosporine

UK-63,052 complex, a new group of quinomycin-like antibiotics comprising UK-63,052 (factor A), UK-63,598 (factor C), UK-65,662 (factor B) and several uncharacterised minor components, is produced by a new subspecies of the genus Streptomyces for which the name Streptomyces braegensis Dietz subsp. japonicus, is proposed. The strain, N617-29, is characterised by a negative melanin reaction, grey aerial mycelium, spiral spore chains and smooth or slightly warty spores. Structure determination has identified UK-63,052, C56H68N10O14S2, UK-63,598, C53H62N10O14S2 and UK-65,662, C55H66N10O14S2 as quinaldic acid substituted quinomycins with unusual bridgehead sulfur substitution as shown in Fig. 3.

Topics: Anti-Bacterial Agents; Echinomycin; Fermentation; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Molecular Structure; Quinoxalines; Soil Microbiology; Spectrophotometry; Streptomyces

The physical and biological roles of the cyclic depsipeptides of actinomycin, quinomycin and triostin antibiotic families are proposed by examining the crystal structures of d(GC)-actinomycin D and d(CGTACG)-triostin A. The analyses suggest that not only are DNA-amino acid hydrogen-bonding and chromophore-base pair stacking crucially important for DNA-antibiotic interaction, but also that the unique structure of the cyclic depsipeptides (the perfect hydrophobic character of the inner surface) is equally necessary to insure that these interactions are directed, unambiguous and screened from interference by solvent. Beyond this, the characteristic nature of the outer surfaces suggests a further hypothesis for the biological role of the cyclic depsipeptide rings; when the antibiotics bind in the region around the pause or rho-dependent termination sites on the DNA, the drugs actually terminate transcription by RNA polymerase and cause release of a premature RNA transcript. Termination is likely because the antibiotics carry five to six consecutive apparent A/T sequences on the surface of the cyclic depsipeptide rings, thus presenting a deceptive termination signal to the polymerase.

Topics: Anti-Bacterial Agents; Base Composition; Base Sequence; Dactinomycin; DNA; Echinomycin; Hydrogen Bonding; Molecular Conformation; Quinoxalines; RNA; Structure-Activity Relationship; Transcription, Genetic

Protoplasts of Streptomyces echinatus have been used to investigate the biosynthesis of echinomycin (quinomycin A). It has been shown that this organism has the capacity to convert a series of triostins to the corresponding quinomycins by a mechanism involving methylation. Evidence is presented which suggests that triostin A is the natural precursor of echinomycin. Conversion of tetra-N-demethyl analogues of triostin A to corresponding analogues of echinomycin was not detected.

Topics: Anti-Bacterial Agents; Carbon Radioisotopes; Echinomycin; Kinetics; Protoplasts; Quinoxalines; Streptomyces; Sulfur Radioisotopes

The kinetics of detergent-induced dissociation of triostins A and C and quinomycin C from DNA have been investigated. All three antibiotics dissociate from poly(dA-dT) and poly(dG-dC) in a simple first-order fashion whereas their dissociation from a natural DNA (calf thymus) is complex, requiring three exponential terms for its complete description. This behaviour is attributed to sequence-selectivity on the part of the drugs and seems to represent dissociation from different classes of intercalative binding site. The time constants of dissociation are better resolved for quinomycins than for triostins, consistent with the view that quinomycins are more sequence-specific in their interaction with DNA, but it is not possible to identify any class of binding site with the alternating purine-pyrimidine sequences of the synthetic polydeoxynucleotides. In general, the triostins dissociate an order of magnitude faster than the corresponding quinomycins. This is attributable to a larger entropy of activation, presumably reflecting greater flexibility of the octapeptide ring when the cross-bridge is a disulphide as opposed to the slightly shorter thioacetal found in quinomycins. The longest time constant in the dissociation of each of the four quinoxaline antibiotics from calf thymus DNA correlates well with its antibacterial potency, in agreement with the conclusion that the biological effects result from impairment of the role of DNA as a template for polymerase activity.

Topics: Animals; Anti-Bacterial Agents; Binding Sites; Cattle; DNA; Echinomycin; In Vitro Techniques; Kinetics; Quinoxalines; Structure-Activity Relationship; Thermodynamics

Topics: Amino Acids; Anti-Bacterial Agents; Chemistry Techniques, Analytical; Echinomycin; Isoleucine; Research

Topics: Actinobacteria; Actinomyces; Animals; Anti-Bacterial Agents; Chemoprevention; Echinomycin; Mice; Poliomyelitis

Topics: Anti-Bacterial Agents; Chloramphenicol; Echinomycin

Topics: Anti-Bacterial Agents; Echinomycin; Quinoxalines