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1.
Scientifica (Cairo) ; 2023: 8846387, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38146491

RESUMEN

The cytotoxic properties of two extracts from Chenopodium quinoa Willd. and three synthetic sapogenins were evaluated in different cancer cell lines (A549, SH-SY5Y, HepG2, and HeLa) to investigate their cytotoxic effects and determine if these cell lines activate the caspase pathway for apoptosis in response to saponin and sapogenin treatment. The saponin extracts were isolated from the agro-industrial waste of Chenopodium quinoa Willd., while the sapogenins were identified and quantitatively determined by High-Performance Liquid Chromatography (HPLC). Among these compounds, ursolic acid was the most active compound, with high IC50 values measured in all cell lines. In addition, hederagenin demonstrated higher caspase-3 activity than staurosporine in HeLa cells, suggesting an anti-cytotoxic activity via a caspase-dependent apoptosis pathway. HPLC analysis showed that the concentration of hederagenin was higher than that of oleanolic acid in ethanolic extracts of white and red quinoa. The ethanolic extracts of white and red quinoa did not show cytotoxic activity. On the other hand, the synthetic sapogenins such as ursolic acid, oleanolic acid, and hederagenin significantly decreased the viability of the four cell lines studied. Finally, by Caspase-3 assay, it was found that HeLa undergoes apoptosis during cell death because hederagenin produces a significant increase in PARP-1 hydrolysis in HeLa cells.

2.
Metabolites ; 13(10)2023 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-37887416

RESUMEN

Three novel lipopeptides, PM130391 (1), PM130392 (2), and PM140293 (3) were obtained from cultures of Streptomyces tuirus PHM034 isolated from a marine sediment. Structural elucidation of the three compounds showed they belong to the nonribosomal peptides family, and they all contain an acylated alanine, three piperazic acids, a methylated glycine, and an N-hydroxylated alanine. The difference between the three compounds resides in the acyl chain bound to the alanine residue. All three compounds showed cytotoxic activity against human cancer cell lines. Genome sequence and bioinformatics analysis allowed the identification of the gene cluster responsible for the biosynthesis. Inactivation of a nonribosomal peptide synthase of this cluster abolished the biosynthesis of the three compounds, thus demonstrating the involvement of this cluster in the biosynthesis of these lipopeptides.

3.
Int J Mol Sci ; 24(9)2023 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-37175904

RESUMEN

Genome mining using standard bioinformatics tools has allowed for the uncovering of hidden biosynthesis gene clusters for specialized metabolites in Streptomyces genomes. In this work, we have used an alternative approach consisting in seeking "Streptomyces Antibiotic Regulatory Proteins" (SARP) encoding genes and analyzing their surrounding DNA region to unearth cryptic gene clusters that cannot be identified using standard bioinformatics tools. This strategy has allowed the unveiling of the new ahb cluster in Streptomyces argillaceus, which had not been retrieved before using antiSMASH. The ahb cluster is highly preserved in other Streptomyces strains, which suggests a role for their encoding compounds in specific environmental conditions. By combining overexpression of three regulatory genes and generation of different mutants, we were able to activate the ahb cluster, and to identify and chemically characterize the encoded compounds that we have named ahbamycins (AHBs). These constitute a new family of metabolites derived from 3-amino-4-hydroxybenzoate (3,4-AHBA) known for having antibiotic and antitumor activity. Additionally, by overexpressing three genes of the cluster (ahbH, ahbI, and ahbL2) for the synthesis and activation of 3,4-AHBA, a new hybrid compound, AHB18, was identified which had been produced from a metabolic crosstalk between the AHB and the argimycin P pathways. The identification of this new BGC opens the possibility to generate new compounds by combinatorial biosynthesis.


Asunto(s)
Antibacterianos , Streptomyces , Antibacterianos/química , Factores de Transcripción/metabolismo , Familia de Multigenes , Genes Reguladores , Streptomyces/genética , Streptomyces/metabolismo , Hidroxibenzoatos/metabolismo
4.
J Environ Sci Health B ; 58(4): 294-303, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36636021

RESUMEN

In the altiplano zone of Latin America, "Chacco" is one of the clays widely consumed as part of geophagy. The objectives of the study were to chemically characterize "Chacco", determine the zero charge point, evaluate the release of aluminum in vitro, perform the kinetic study and evaluate the health risk. The results by ICP-OES showed that the elements with the highest concentration were Al, Ba, Ca, Fe, K, Mg, Mn, Na, Si, Sr, Ti and Zn. ATR-FTIR analysis showed the presence of Si-O (693 and 990 cm-1), Al-O (790 cm-1), Al-Al-OH bending vibration (912 cm-1), Si-H bond stretching (2100 to 2500 cm-1) and free -OH groups (3629 cm-1). SEM-EDX results indicate that Al is one of the main constituents of "Chacco" (7.35 wt%). The pHzpc of "Chacco" was 6.83. In the dissolution profiles, the highest Al release occurred at pH 6.8 and in intestinal juice simulated with pseudo-second order dissolution kinetics. The EDIAl and EWIAl were 20.24 and 142.66 respectively, comparing EWIAl with the PTWI established by JECFA (2 mg/kg bw), it is concluded that the weekly intake of "Chacco" represents an appreciable health risk. There are no reports of the carcinogenic factor of Al, so TRAl was not calculated.


Asunto(s)
Aluminio , Pica , Humanos , Arcilla , Perú , Medición de Riesgo
5.
ACS Chem Biol ; 17(8): 2320-2331, 2022 08 19.
Artículo en Inglés | MEDLINE | ID: mdl-35830174

RESUMEN

Largimycins A1 and A2 are key members of a recently identified family of hybrid nonribosomal peptide polyketides belonging to the scarcely represented group of antitumor leinamycins. They are encoded by the gene cluster lrg of Streptomyces argillaceus. This cluster contains a halogenase gene and two sets of genes for the biosynthesis and incorporation of ß branches at C3 and C9. Noticeably, largimycins A1 and A2 are nonhalogenated compounds and only contain a ß branch at C3. By generating mutants in those genes and characterizing chemically their accumulated compounds, we could confirm the existence of a chlorination step at C19, the introduction of an acetyl-derived olefinic exomethylene group at C9, and a propionyl-derived ß branch at C3 in the biosynthesis pathway. Since the olefinic exomethylene group and the chlorine atom are absent in the final products, those biosynthetic steps can be considered cryptic in the overall pathway but essential to generating keto and epoxide functionalities at C9 and C18/C19, respectively. We propose that chlorination at C19 is utilized as an activation strategy that creates the precursor halohydrin to finally yield the epoxy functionality at C18/C19. This represents a novel strategy to create such functionalities and extends the small number of natural product biosynthetic pathways that include a cryptic chlorination step.


Asunto(s)
Halogenación , Streptomyces , Alquilación , Lactamas , Macrólidos , Familia de Multigenes , Streptomyces/genética , Streptomyces/metabolismo , Tiazoles , Tionas
6.
Chemistry ; 28(54): e202201644, 2022 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-35748487

RESUMEN

A nickel-catalysed reductive cross-coupling reaction between benzyl sulfonium salts and benzyl bromides is reported. Simple, stable and readily available sulfonium salts have shown their ability as leaving groups in cross-electrophile coupling, allowing the formation of challenging sp3 -sp3 carbon-carbon bonds, towards the synthesis of interesting dihydrostilbene derivatives. In addition, benzyl tosyl derivatives have been demonstrated to be suitable substrates for reductive cross-coupling by in-situ formation of the corresponding sulfonium salt.


Asunto(s)
Níquel , Sales (Química) , Compuestos de Bencilo , Bromuros/química , Carbono/química , Catálisis , Níquel/química
7.
J Environ Sci Health B ; 57(4): 297-304, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35277121

RESUMEN

In Peru, rice grains, wheat, and their processed products are accessible due to their low cost; however, their sale does not have quality certification, so their safety is not guaranteed. This study quantified lead (Pb) and cadmium (Cd) by voltammetry in 16 samples of grains and processed products from four markets in Arequipa (Altiplano, Andrés Avelino Cáceres, Los Incas, and San Camilo) and evaluated their potential health risk. The maximum concentrations of Pb in rice, wheat, and their processed products were 4.821 mg/kg, 7.962 mg/kg, 4.717 mg/kg, and 6.440 mg/kg, respectively; only seven samples showed Cd. All samples exceeded the maximum level (ML) for Pb, and four samples exceeded the ML for Cd established by the Codex Alimentarius (0.200 mg/kg); the rice product had the highest concentration of Pb and Cd. In relation to the estimation of potential health risk, the estimated daily intake (EDI), target hazard quotient (THQ), and target cancer risk (TR), showed that the consumption of all processed rice and wheat products (except Andrés Avelino Cáceres rice and San Camilo wheat) represent a health threat associated with an increased probability of cancer development.


Asunto(s)
Metales Pesados , Neoplasias , Oryza , Contaminantes del Suelo , Cadmio/análisis , Cadmio/toxicidad , Monitoreo del Ambiente , Contaminación de Alimentos/análisis , Humanos , Plomo/toxicidad , Metales Pesados/análisis , Perú , Medición de Riesgo , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidad , Triticum
8.
Front Microbiol ; 13: 742168, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35185841

RESUMEN

The World Health Organization warns that the alarming increase in antibiotic resistant bacteria will lead to 2.7 million deaths annually due to the lack of effective antibiotic therapies. Clearly, there is an urgent need for short-term alternatives that help to alleviate these alarming figures. In this respect, the scientific community is exploring neglected ecological niches from which the prototypical antibiotic-producing bacteria Streptomycetes are expected to be present. Recent studies have reported that honeybees and their products carry Streptomyces species that possess strong antibacterial activity. In this study, we have investigated the antibiotic profile of two Streptomycetes strains that were isolated from beehives. One of the isolates is the strain Streptomyces albus AN1, which derives from pollen, and shows potent antimicrobial activity against Candida albicans. The other isolate is the strain Streptomyces griseoaurantiacus AD2, which was isolated from honey, and displays a broad range of antimicrobial activity against different Gram-positive bacteria, including pathogens such as Staphylococcus aureus and Enterococus faecalis. Cultures of S. griseoaurantiacus AD2 have the capacity to produce the antibacterial compounds undecylprodigiosin and manumycin, while those of S. albus AN1 accumulate antifungal compounds such as candicidins and antimycins. Furthermore, genome and dereplication analyses suggest that the number of putative bioactive metabolites produced by AD2 and AN1 is considerably high, including compounds with anti-microbial and anti-cancer properties. Our results postulate that beehives are a promising source for the discovery of novel bioactive compounds that might be of interest to the agri-food sector and healthcare pharmaceuticals.

9.
Microb Cell Fact ; 19(1): 111, 2020 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-32448325

RESUMEN

BACKGROUND: Mithramycin is an anti-tumor compound of the aureolic acid family produced by Streptomyces argillaceus. Its biosynthesis gene cluster has been cloned and characterized, and several new analogs with improved pharmacological properties have been generated through combinatorial biosynthesis. To further study these compounds as potential new anticancer drugs requires their production yields to be improved significantly. The biosynthesis of mithramycin proceeds through the formation of the key intermediate 4-demethyl-premithramycinone. Extensive studies have characterized the biosynthesis pathway from this intermediate to mithramycin. However, the biosynthesis pathway for 4-demethyl-premithramycinone remains unclear. RESULTS: Expression of cosmid cosAR7, containing a set of mithramycin biosynthesis genes, in Streptomyces albus resulted in the production of 4-demethyl-premithramycinone, delimiting genes required for its biosynthesis. Inactivation of mtmL, encoding an ATP-dependent acyl-CoA ligase, led to the accumulation of the tricyclic intermediate 2-hydroxy-nogalonic acid, proving its essential role in the formation of the fourth ring of 4-demethyl-premithramycinone. Expression of different sets of mithramycin biosynthesis genes as cassettes in S. albus and analysis of the resulting metabolites, allowed the reconstitution of the biosynthesis pathway for 4-demethyl-premithramycinone, assigning gene functions and establishing the order of biosynthetic steps. CONCLUSIONS: We established the biosynthesis pathway for 4-demethyl-premithramycinone, and identified the minimal set of genes required for its assembly. We propose that the biosynthesis starts with the formation of a linear decaketide by the minimal polyketide synthase MtmPKS. Then, the cyclase/aromatase MtmQ catalyzes the cyclization of the first ring (C7-C12), followed by formation of the second and third rings (C5-C14; C3-C16) catalyzed by the cyclase MtmY. Formation of the fourth ring (C1-C18) requires MtmL and MtmX. Finally, further oxygenation and reduction is catalyzed by MtmOII and MtmTI/MtmTII respectively, to generate the final stable tetracyclic intermediate 4-demethyl-premithramycinone. Understanding the biosynthesis of this compound affords enhanced possibilities to generate new mithramycin analogs and improve their production titers for bioactivity investigation.


Asunto(s)
Antibióticos Antineoplásicos/biosíntesis , Plicamicina/biosíntesis , Policétidos/metabolismo , Streptomyces , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Streptomyces/genética , Streptomyces/metabolismo
10.
Angew Chem Int Ed Engl ; 57(31): 9785-9789, 2018 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-29882623

RESUMEN

An interrupted Pummerer/nickel-catalysed cross-coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one-pot process, involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp-, sp2 -, and sp3 -hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo- and heterocyclic alkenyl sulfonium salts for cross-coupling.

11.
Molecules ; 22(10)2017 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-29057800

RESUMEN

Four novel paulomycin derivatives have been isolated from S. albus J1074 grown in MFE culture medium. These compounds are structural analogs of antibiotics 273a2α and 273a2ß containing a thiazole moiety, probably originated through an intramolecular Michael addition. The novel, thiazole, moiety-containing paulomycins show a lower antibiotic activity than paulomycins A and B against Gram-positive bacteria. However, two of them show an improved activity against Gram-negative bacteria. In addition, the four novel compounds are more stable in culture than paulomycins A and B. Thus, the presence of an N-acetyl-l-cysteine moiety linked to the carbon atom of the paulic acid isothiocyanate moiety, via a thioester bond, and the subsequent intramolecular cyclization of the paulic acid to generate a thiazole heterocycle confer to paulomycins a higher structural stability that otherwise will conduce to paulomycin degradation and into inactive paulomenols.


Asunto(s)
Antibacterianos/química , Antibacterianos/aislamiento & purificación , Streptomyces/química , Tiazoles/química , Antibacterianos/uso terapéutico , Ciclohexenos/química , Ciclohexenos/farmacología , Disacáridos/química , Disacáridos/farmacología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/patogenicidad , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/patogenicidad , Humanos , Tiazoles/aislamiento & purificación , Tiazoles/uso terapéutico
12.
Microb Cell Fact ; 15(1): 187, 2016 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-27829451

RESUMEN

BACKGROUND: Antitumor compounds PM100117 and PM100118 are glycosylated polyketides derived from the marine actinobacteria Streptomyces caniferus GUA-06-05-006A. The organization and characterization of the PM100117/18 biosynthesis gene cluster has been recently reported. RESULTS: Based on the preceding information and new genetic engineering data, we have outlined the pathway by which PM100117/18 are glycosylated. Furthermore, these genetic engineering experiments have allowed the generation of novel PM100117/18 analogues. Deletion of putative glycosyltranferase genes and additional genes presumably involved in late biosynthesis steps of the three 2,6-dideoxysugars appended to the PM100117/18 polyketide skeleton, resulted in the generation of a series of intermediates and novel derivatives. CONCLUSIONS: Isolation and identification of the novel compounds constitutes an important contribution to our knowledge on PM100117/18 glycosylation, and set the basis for further characterization of specific enzymatic reactions, additional genetic engineering and combinatorial biosynthesis approaches.


Asunto(s)
Antineoplásicos/metabolismo , Ingeniería Genética/métodos , Macrólidos/metabolismo , Células A549 , Antineoplásicos/farmacología , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Eliminación de Gen , Glicosilación , Glicosiltransferasas/genética , Glicosiltransferasas/metabolismo , Células HT29 , Humanos , Macrólidos/farmacología , Streptomyces/genética , Streptomyces/metabolismo
13.
Microb Cell Fact ; 15: 44, 2016 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-26905289

RESUMEN

BACKGROUND: PM100117 and PM100118 are glycosylated polyketides with remarkable antitumor activity, which derive from the marine symbiotic actinobacteria Streptomyces caniferus GUA-06-05-006A. Structurally, PM100117 and PM100118 are composed of a macrocyclic lactone, three deoxysugar units and a naphthoquinone (NQ) chromophore that shows a clear structural similarity to menaquinone. RESULTS: Whole-genome sequencing of S. caniferus GUA-06-05-006A has enabled the identification of PM100117 and PM100118 biosynthesis gene cluster, which has been characterized on the basis of bioinformatics and genetic engineering data. The product of four genes shows high identity to proteins involved in the biosynthesis of menaquinone via futalosine. Deletion of one of these genes led to a decay in PM100117 and PM100118 production, and to the accumulation of several derivatives lacking NQ. Likewise, five additional genes have been genetically characterized to be involved in the biosynthesis of this moiety. Moreover, the generation of a mutant in a gene coding for a putative cytochrome P450 has led to the production of PM100117 and PM100118 structural analogues showing an enhanced in vitro cytotoxic activity relative to the parental products. CONCLUSIONS: Although a number of compounds structurally related to PM100117 and PM100118 has been discovered, this is, to our knowledge, the first insight reported into their biosynthesis. The structural resemblance of the NQ moiety to menaquinone, and the presence in the cluster of four putative menaquinone biosynthetic genes, suggests a connection between the biosynthesis pathways of both compounds. The availability of the PM100117 and PM100118 biosynthetic gene cluster will surely pave a way to the combinatorial engineering of more derivatives.


Asunto(s)
Actinobacteria/genética , Antineoplásicos/farmacología , Vías Biosintéticas/genética , Ingeniería Genética/métodos , Macrólidos/farmacología , Familia de Multigenes/genética , Agua de Mar/microbiología , Actinobacteria/efectos de los fármacos , Antineoplásicos/química , Transporte Biológico/efectos de los fármacos , Vías Biosintéticas/efectos de los fármacos , Carbohidratos/biosíntesis , Carbohidratos/química , Biología Computacional , Simulación por Computador , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Genoma Bacteriano , Macrólidos/química , Naftoquinonas/química , Naftoquinonas/metabolismo , Análisis de Secuencia de ADN
14.
Planta Med ; 81(15): 1326-38, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26393942

RESUMEN

Mithramycin is an antitumor compound of the aureolic acid family produced by Streptomyces argillaceus. It has been used to treat several types of cancer including testicular carcinoma, chronic and acute myeloid leukemia as well as hypercalcemias and Paget's disease. Although the use of mithramycin in humans has been limited because its side effects, in recent years a renewed interest has arisen since new uses and activities have been ascribed to it. Chemically, mithramycin is characterized by a tricyclic aglycone bearing two aliphatic side chains attached at C3 and C7, and disaccharide and trisaccharide units attached at positions 2 and 6, respectively. The mithramycin gene cluster has been characterized. This has allowed for the development of several mithramycin analogs ("mithralogs") by combinatorial biosynthesis and/or biocatalysis. The combinatorial biosynthesis strategies include gene inactivation and/or the use of sugar biosynthesis plasmids for sugar modification. In addition, lipase-based biocatalysis enabled selective modifications of the hydroxyl groups, providing further mithramycin analogs. As a result, new mithramycin analogs with higher antitumor activity and/or less toxicity have been generated. One, demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK (EC-8042), is being tested in regulatory preclinical assays, representing an opportunity to open the therapeutic window of this promising molecular scaffold.


Asunto(s)
Antibióticos Antineoplásicos/química , Plicamicina/análogos & derivados , Animales , Antibióticos Antineoplásicos/uso terapéutico , Biocatálisis , Técnicas Químicas Combinatorias , Humanos , Plicamicina/química , Plicamicina/uso terapéutico , Streptomyces/química
15.
Chembiochem ; 16(10): 1461-73, 2015 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-25892546

RESUMEN

Streptomyces sp. Tü 6176 produces the cytotoxic benzoxazole nataxazole. Bioinformatic analysis of the genome of this organism predicts the presence of 38 putative secondary-metabolite biosynthesis gene clusters, including those involved in the biosynthesis of AJI9561 and its derivative nataxazole, the antibiotic hygromycin B, and ionophores enterobactin and coelibactin. The nataxazole biosynthesis gene cluster was identified and characterized: it lacks the O-methyltransferase gene required to convert AJI9561 into nataxazole. This O-methyltransferase activity might act as a resistance mechanism, as AJI9561 shows antibiotic activity whereas nataxazole is inactive. Moreover, heterologous expression of the nataxazole biosynthesis gene cluster in S. lividans JT46 resulted in the production of AJI9561. Nataxazole biosynthesis requires the shikimate pathway to generate 3-hydroxyanthranilate and an iterative type I PKS to generate 6-methylsalicylate. Production of nataxazole was improved up to fourfold by disrupting one regulatory gene in the cluster. An additional benzoxazole, 5-hydroxynataxazole is produced by Streptomyces sp. Tü 6176. 5-Hydroxynataxazole derives from nataxazole by the activity of an as yet unidentified oxygenase; this implies cross-talk between the nataxazole biosynthesis pathway and an unknown pathway.


Asunto(s)
Antibacterianos/metabolismo , Benzoxazoles/metabolismo , Vías Biosintéticas , Familia de Multigenes , Streptomyces/enzimología , Streptomyces/genética , Animales , Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Infecciones Bacterianas/tratamiento farmacológico , Benzoxazoles/farmacología , Línea Celular Tumoral , Regulación Bacteriana de la Expresión Génica , Genes Bacterianos , Humanos , Ratones , Células 3T3 NIH , Streptomyces/metabolismo
16.
Chemistry ; 21(10): 3906-9, 2015 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-25611197

RESUMEN

A general methodology for the α-arylation of ketones using a nickel catalyst has been developed. The new well-defined [Ni(IPr*)(cin)Cl] (1 c) pre-catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised aryl chlorides. This cinnamyl-based Ni-N-heterocyclic carbene (NHC) complex has demonstrated a different behaviour to previously reported NHC-Ni catalysts. Preliminary mechanistic studies suggest a Ni(0)/Ni(II) catalytic cycle to be at play.


Asunto(s)
Complejos de Coordinación/química , Hidrocarburos Clorados/química , Cetonas/química , Metano/análogos & derivados , Níquel/química , Catálisis , Cloruros , Metano/química , Estructura Molecular
17.
Genome Announc ; 2(4)2014 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-24994793

RESUMEN

Streptomyces sp. strain NTK 937 is the producer of the benzoxazole antibiotic caboxamycin, which has been shown to exert inhibitory activity against Gram-positive bacteria, cytotoxic activity against several human tumor cell lines, and inhibition of the enzyme phosphodiesterase. In this genome announcement, we present a draft genome sequence of Streptomyces sp. NTK 937 in which we identified at least 35 putative secondary metabolite biosynthetic gene clusters.

18.
Microbiology (Reading) ; 160(Pt 3): 467-478, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24353310

RESUMEN

Two putative pathway-specific regulators have been identified in the collismycin A gene cluster: ClmR1, belonging to the TetR-family, and the LuxR-family transcriptional regulator ClmR2. Inactivation of clmR1 led to a moderate increase of collismycin A yields along with an early onset of its production, suggesting an inhibitory role for the product of this gene. Inactivation of clmR2 abolished collismycin A biosynthesis, whereas overexpression of ClmR2 led to a fourfold increase in production yields, indicating that ClmR2 is an activator of collismycin A biosynthesis. Expression analyses of the collismycin gene cluster in the wild-type strain and in ΔclmR1 and ΔclmR2 mutants confirmed the role proposed for both regulatory genes, revealing that ClmR2 positively controls the expression of most of the genes in the cluster and ClmR1 negatively regulates both its own expression and that of clmR2. Additionally, production assays and further transcription analyses confirmed the existence of a higher regulatory level modulating collismycin A biosynthesis in response to iron concentrations in the culture medium. Thus, high iron levels inhibit collismycin A biosynthesis through the repression of clmR2 transcription. These results have allowed us to propose a regulatory model that integrates the effect of iron as the main environmental stimulus controlling collismycin A biosynthesis.


Asunto(s)
2,2'-Dipiridil/análogos & derivados , Hierro/metabolismo , Redes y Vías Metabólicas , Streptomyces/metabolismo , Factores de Transcripción/genética , 2,2'-Dipiridil/metabolismo , Secuencia de Aminoácidos , Regulación Bacteriana de la Expresión Génica , Orden Génico , Datos de Secuencia Molecular , Familia de Multigenes , Alineación de Secuencia , Streptomyces/genética , Factores de Transcripción/química , Factores de Transcripción/metabolismo
19.
Metab Eng ; 20: 187-97, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24148183

RESUMEN

Mithramycin (MTM) is a polyketide antitumor compound produced by Streptomyces argillaceus constituted by a tricyclic aglycone with two aliphatic side chains, a trisaccharide and a disaccharide chain. The biosynthesis of the polyketide aglycone is initiated by the condensation of ten malonyl-CoA units to render a carbon chain that is modified to a tetracyclic intermediate and sequentially glycosylated by five deoxysugars originated from glucose-1-phosphate. Further oxidation and reduction render the final compound. We aimed to increase the precursor supply of malonyl-CoA and/or glucose-1-phosphate in S. argillaceus to enhance MTM production. We have shown that by overexpressing either the S. coelicolor phosphoglucomutase gene pgm or the acetyl-CoA carboxylase ovmGIH genes from the oviedomycin biosynthesis gene cluster in S. argillaceus, we were able to increase the intracellular pool of glucose-1-phosphate and malonyl-CoA, respectively. Moreover, we have cloned the S. argillaceus ADP-glucose pyrophosphorylase gene glgCa and the acyl-CoA:diacylglycerol acyltransferase gene aftAa, and we showed that by inactivating them, an increase of the intracellular concentration of glucose-1-phosphate/glucose-6-phosphate and malonyl-CoA/acetyl-CoA was observed, respectively. Each individual modification resulted in an enhancement of MTM production but the highest production level was obtained by combining all strategies together. In addition, some of these strategies were successfully applied to increase production of four MTM derivatives with improved pharmacological properties: demycarosyl-mithramycin, demycarosyl-3D-ß-D-digitoxosyl-mithramycin, mithramycin SK and mithramycin SDK.


Asunto(s)
Antibióticos Antineoplásicos/biosíntesis , Glucofosfatos , Malonil Coenzima A , Ingeniería Metabólica , Plicamicina/biosíntesis , Streptomyces , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Glucofosfatos/genética , Glucofosfatos/metabolismo , Malonil Coenzima A/genética , Malonil Coenzima A/metabolismo , Streptomyces/genética , Streptomyces/metabolismo
20.
Chem Biol ; 20(8): 1022-32, 2013 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-23911584

RESUMEN

Collismycin A is a member of the 2,2'-bipyridyl family of natural products that shows cytotoxic activity. Structurally, it belongs to the hybrid polyketides-nonribosomal peptides. After the isolation and characterization of the collismycin A gene cluster, we have used the combination of two different approaches (insertional inactivation and biocatalysis) to increase structural diversity in this natural product class. Twelve collismycin analogs were generated with modifications in the second pyridine ring of collismycin A, thus potentially maintaining biologic activity. None of these analogs showed better cytotoxic activity than the parental collismycin. However, some analogs showed neuroprotective activity and one of them (collismycin H) showed better values for neuroprotection against oxidative stress in a zebrafish model than those of collismycin A. Interestingly, this analog also showed very poor cytotoxic activity, a feature very desirable for a neuroprotectant compound.


Asunto(s)
2,2'-Dipiridil/análogos & derivados , Fármacos Neuroprotectores/metabolismo , Streptomyces/genética , Streptomyces/metabolismo , 2,2'-Dipiridil/química , 2,2'-Dipiridil/metabolismo , 2,2'-Dipiridil/farmacología , Animales , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacología , Vías Biosintéticas , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Genes Bacterianos , Ingeniería Genética , Humanos , Familia de Multigenes , Fármacos Neuroprotectores/química , Fármacos Neuroprotectores/farmacología , Pez Cebra
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