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Tirkkonen H, Brown KV, Niemczura M, Faudemer Z, Brown C, Ponomareva LV, Helmy YA, Thorson JS, Nybo SE, Metsä-Ketelä M, Shaaban KA. Engineering BioBricks for Deoxysugar Biosynthesis and Generation of New Tetracenomycins. ACS OMEGA 2023; 8:21237-21253. [PMID: 37332790 PMCID: PMC10269268 DOI: 10.1021/acsomega.3c02460] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023]
Abstract
Tetracenomycins and elloramycins are polyketide natural products produced by several actinomycetes that exhibit antibacterial and anticancer activities. They inhibit ribosomal translation by binding in the polypeptide exit channel of the large ribosomal subunit. The tetracenomycins and elloramycins are typified by a shared oxidatively modified linear decaketide core, yet they are distinguished by the extent of O-methylation and the presence of a 2',3',4'-tri-O-methyl-α-l-rhamnose appended at the 8-position of elloramycin. The transfer of the TDP-l-rhamnose donor to the 8-demethyl-tetracenomycin C aglycone acceptor is catalyzed by the promiscuous glycosyltransferase ElmGT. ElmGT exhibits remarkable flexibility toward transfer of many TDP-deoxysugar substrates to 8-demethyltetracenomycin C, including TDP-2,6-dideoxysugars, TDP-2,3,6-trideoxysugars, and methyl-branched deoxysugars in both d- and l-configurations. Previously, we developed an improved host, Streptomyces coelicolor M1146::cos16F4iE, which is a stable integrant harboring the required genes for 8-demethyltetracenomycin C biosynthesis and expression of ElmGT. In this work, we developed BioBricks gene cassettes for the metabolic engineering of deoxysugar biosynthesis in Streptomyces spp. As a proof of concept, we used the BioBricks expression platform to engineer biosynthesis for d-configured TDP-deoxysugars, including known compounds 8-O-d-glucosyl-tetracenomycin C, 8-O-d-olivosyl-tetracenomycin C, 8-O-d-mycarosyl-tetracenomycin C, and 8-O-d-digitoxosyl-tetracenomycin C. In addition, we generated four new tetracenomycins including one modified with a ketosugar, 8-O-4'-keto-d-digitoxosyl-tetracenomycin C, and three modified with 6-deoxysugars, including 8-O-d-fucosyl-tetracenomycin C, 8-O-d-allosyl-tetracenomycin C, and 8-O-d-quinovosyl-tetracenomycin C. Our work demonstrates the feasibility of BioBricks cloning, with the ability to recycle intermediate constructs, for the rapid assembly of diverse carbohydrate pathways and glycodiversification of a variety of natural products.
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Affiliation(s)
- Heli Tirkkonen
- Department
of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Katelyn V. Brown
- Department
of Pharmaceutical Sciences, College of Pharmacy, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Magdalena Niemczura
- Department
of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Zélie Faudemer
- Chemistry
and Chemical Engineering Department, SIGMA
Clermont, 63170 Aubière, France
| | - Courtney Brown
- Department
of Pharmaceutical Sciences, College of Pharmacy, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Larissa V. Ponomareva
- Center for Pharmaceutical Research and Innovation,
College
of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Yosra A. Helmy
- Department
of Veterinary Science, College of Agriculture, Food, and Environment, University of Kentucky, Lexington, Kentucky 40546, United States
| | - Jon S. Thorson
- Center for Pharmaceutical Research and Innovation,
College
of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - S. Eric Nybo
- Department
of Pharmaceutical Sciences, College of Pharmacy, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Mikko Metsä-Ketelä
- Department
of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Khaled A. Shaaban
- Center for Pharmaceutical Research and Innovation,
College
of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
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WANG H, WANG L, FAN K, PAN G. Tetracycline natural products: discovery, biosynthesis and engineering. Chin J Nat Med 2022; 20:773-794. [DOI: 10.1016/s1875-5364(22)60224-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Indexed: 11/03/2022]
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Li LY, Hu YL, Sun JL, Yu LB, Shi J, Wang ZR, Guo ZK, Zhang B, Guo WJ, Tan RX, Ge HM. Resistance and phylogeny guided discovery reveals structural novelty of tetracycline antibiotics. Chem Sci 2022; 13:12892-12898. [DOI: 10.1039/d2sc03965f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022] Open
Abstract
Using resistance gene genome mining strategy and refinement with chain length factor, we obtained 25 distinct tetracycline biosynthetic gene clusters and a novel tetracycline. The biosynthesis of the highly modified tetracycline was investigated.
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Affiliation(s)
- Ling Yu Li
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Yi Ling Hu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Jia Lin Sun
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Long Bo Yu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Jing Shi
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Zi Ru Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Zhi Kai Guo
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Bio-technology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Bo Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Wen Jie Guo
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Ren Xiang Tan
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Hui Ming Ge
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
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Kormanec J, Novakova R, Csolleiova D, Feckova L, Rezuchova B, Sevcikova B, Homerova D. The antitumor antibiotic mithramycin: new advanced approaches in modification and production. Appl Microbiol Biotechnol 2020; 104:7701-7721. [DOI: 10.1007/s00253-020-10782-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022]
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Zabala D, Song L, Dashti Y, Challis GL, Salas JA, Méndez C. Heterologous reconstitution of the biosynthesis pathway for 4-demethyl-premithramycinone, the aglycon of antitumor polyketide mithramycin. Microb Cell Fact 2020; 19:111. [PMID: 32448325 PMCID: PMC7247220 DOI: 10.1186/s12934-020-01368-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/15/2020] [Indexed: 02/07/2023] Open
Abstract
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.
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Affiliation(s)
- Daniel Zabala
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), University of Oviedo, Oviedo, Spain
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Lijiang Song
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Yousef Dashti
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Gregory L Challis
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, CV4 7AL, UK
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, 3800, Australia
| | - José A Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), University of Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain
| | - Carmen Méndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), University of Oviedo, Oviedo, Spain.
- Instituto de Investigación Sanitaria de Asturias (ISPA), Oviedo, Spain.
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Ke J, Yoshikuni Y. Multi-chassis engineering for heterologous production of microbial natural products. Curr Opin Biotechnol 2019; 62:88-97. [PMID: 31639618 DOI: 10.1016/j.copbio.2019.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/30/2019] [Accepted: 09/09/2019] [Indexed: 12/11/2022]
Abstract
Microbial genomes encode numerous biosynthetic gene clusters (BGCs) that may produce natural products with diverse applications in medicine, agriculture, the environment, and materials science. With the advent of genome sequencing and bioinformatics, heterologous expression of BGCs is of increasing interest in bioactive natural product (NP) discovery. However, this approach has had limited success because expression of BGCs relies heavily on the physiology of just a few commonly available host chassis. Expanding and diversifying the chassis portfolio for heterologous BGC expression may greatly increase the chances for successful NP production. In this review, we first discuss genetic and genome engineering technologies used to clone, modify, and transform BGCs into multiple strains and to engineer chassis strains. We then highlight studies that employed the multi-chassis approach successfully to optimize NP production, discover previously uncharacterized NPs, and better understand BGC function.
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Affiliation(s)
- Jing Ke
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, CA 94598, USA
| | - Yasuo Yoshikuni
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, CA 94598, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Center for Advanced Bioenergy and Bioproducts Innovation, Urbana, IL 61801, USA; Global Institution for Collaborative Research and Education, Hokkaido University, Hokkaido, 060-8589, Japan.
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Salcedo RG, Olano C, Fernández R, Braña AF, Méndez C, de la Calle F, Salas JA. Elucidation of the glycosylation steps during biosynthesis of antitumor macrolides PM100117 and PM100118 and engineering for novel derivatives. Microb Cell Fact 2016; 15:187. [PMID: 27829451 PMCID: PMC5103430 DOI: 10.1186/s12934-016-0591-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 11/03/2016] [Indexed: 03/14/2023] Open
Abstract
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.
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Affiliation(s)
- Raúl García Salcedo
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Asturias, 33006, Oviedo, Spain
| | - Carlos Olano
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Asturias, 33006, Oviedo, Spain
| | - Rogelio Fernández
- Drug Discovery Area, PharmaMar S.A., Avda. de los Reyes, Colmenar Viejo, 128770, Madrid, Spain
| | - Alfredo F Braña
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Asturias, 33006, Oviedo, Spain
| | - Carmen Méndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Asturias, 33006, Oviedo, Spain
| | - Fernando de la Calle
- Drug Discovery Area, PharmaMar S.A., Avda. de los Reyes, Colmenar Viejo, 128770, Madrid, Spain
| | - José A Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Asturias, 33006, Oviedo, Spain.
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Peltier-Pain P, Singh S, Thorson JS. Characterization of Early Enzymes Involved in TDP-Aminodideoxypentose Biosynthesis en Route to Indolocarbazole AT2433. Chembiochem 2015; 16:2141-6. [PMID: 26289554 PMCID: PMC4598305 DOI: 10.1002/cbic.201500365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Indexed: 01/29/2023]
Abstract
The characterization of TDP-α-D-glucose dehydrogenase (AtmS8), TDP-α-D-glucuronic acid decarboxylase (AtmS9), and TDP-4-keto-α-D-xylose 2,3-dehydratase (AtmS14), involved in Actinomadura melliaura AT2433 aminodideoxypentose biosynthesis, is reported. This study provides the first biochemical evidence that both deoxypentose and deoxyhexose biosynthetic pathways share common strategies for sugar 2,3-dehydration/reduction and implicates the sugar nucleotide base specificity of AtmS14 as a potential mechanism for sugar nucleotide commitment to secondary metabolism. In addition, a re-evaluation of the AtmS9 homologue involved in calicheamicin aminodeoxypentose biosynthesis (CalS9) reveals that CalS9 catalyzes UDP-4-keto-α-D-xylose as the predominant product, rather than UDP-α-D-xylose as previously reported. Cumulatively, this work provides additional fundamental insights regarding the biosynthesis of novel pentoses attached to complex bacterial secondary metabolites.
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Affiliation(s)
- Pauline Peltier-Pain
- Pharmaceutical Sciences Division, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI, 53705, USA
- Glycom A/S, Denmark
| | - Shanteri Singh
- Center for Pharmaceutical Research and Innovation, Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY, 40536, USA
| | - Jon S Thorson
- Center for Pharmaceutical Research and Innovation, Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY, 40536, USA.
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Zhang G, Li Y, Fang L, Pfeifer BA. Tailoring pathway modularity in the biosynthesis of erythromycin analogs heterologously engineered in E. coli. SCIENCE ADVANCES 2015; 1:e1500077. [PMID: 26601183 PMCID: PMC4640655 DOI: 10.1126/sciadv.1500077] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/11/2015] [Indexed: 05/26/2023]
Abstract
Type I modular polyketide synthases are responsible for potent therapeutic compounds that include avermectin (antihelinthic), rapamycin (immunosuppressant), pikromycin (antibiotic), and erythromycin (antibiotic). However, compound access and biosynthetic manipulation are often complicated by properties of native production organisms, prompting an approach (termed heterologous biosynthesis) illustrated in this study through the reconstitution of the erythromycin pathway through Escherichia coli. Using this heterologous system, 16 tailoring pathways were introduced, systematically producing eight chiral pairs of deoxysugar substrates. Successful analog formation for each new pathway emphasizes the remarkable flexibility of downstream enzymes to accommodate molecular variation. Furthermore, analogs resulting from three of the pathways demonstrated bioactivity against an erythromycin-resistant Bacillus subtilis strain. The approach and results support a platform for continued molecular diversification of the tailoring components of this and other complex natural product pathways in a manner that mirrors the modular nature of the upstream megasynthases responsible for aglycone polyketide formation.
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Chen JM, Hou C, Wang G, Tsodikov OV, Rohr J. Structural insight into MtmC, a bifunctional ketoreductase-methyltransferase involved in the assembly of the mithramycin trisaccharide chain. Biochemistry 2015; 54:2481-9. [PMID: 25587924 DOI: 10.1021/bi501462g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
More and more post-PKS tailoring enzymes are recognized as being multifunctional and codependent on other tailoring enzymes. One of the recently discovered intriguing examples is MtmC, a bifunctional TDP-4-keto-d-olivose ketoreductase-methyltransferase, which-in codependence with glycosyltransferase MtmGIV-is a key contributor to the biosynthesis of the critical trisaccharide chain of the antitumor antibiotic mithramycin (MTM), produced by Streptomyces argillaceus. We report crystal structures of three binary complexes of MtmC with its methylation cosubstrate SAM, its coproduct SAH, and a nucleotide TDP as well as crystal structures of two ternary complexes, MtmC-SAH-TDP-4-keto-d-olivose and MtmC-SAM-TDP, in the range of 2.2-2.7 Å resolution. The structures reveal general and sugar-specific recognition and catalytic structural features of MtmC. Depending on the catalytic function that is conducted by MtmC, it must bind either NADPH or SAM in the same cofactor binding pocket. A tyrosine residue (Tyr79) appears as a lid covering the sugar moiety of the substrate during the methyl transfer reaction. This residue swings out of the active site by ~180° in the absence of the substrate. This unique conformational change likely serves to release the methylated product and, possibly, to open the active site for binding the bulkier cosubstrate NADPH prior to the reduction reaction.
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Affiliation(s)
- Jhong-Min Chen
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Caixia Hou
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Guojun Wang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Oleg V Tsodikov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | - Jürgen Rohr
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
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Flores-Ramirez G, Janecek S, Miernyk JA, Skultety L. In silico biosynthesis of virenose, a methylated deoxy-sugar unique to Coxiella burnetii lipopolysaccharide. Proteome Sci 2012; 10:67. [PMID: 23150954 PMCID: PMC3539893 DOI: 10.1186/1477-5956-10-67] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 11/05/2012] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED BACKGROUND Coxiella burnetii is Gram-negative bacterium responsible for the zoonosis Q-fever. While it has an obligate intracellular growth habit, it is able to persist for extended periods outside of a host cell and can resist environmental conditions that would be lethal to most prokaryotes. It is these extracellular bacteria that are the infectious stage encountered by eukaryotic hosts. The intracellular form has evolved to grow and replicate within acidified parasitophorous vacuoles. The outer coat of C. burnetii comprises a complex lipopolysaccharide (LPS) component that includes the unique methylated-6-deoxyhexose, virenose. Although potentially important as a biomarker for C. burnetii, the pathway for its biosynthesis remains obscure. RESULTS The 6-deoxyhexoses constitute a large family integral to the LPS of many eubacteria. It is believed that precursors of the methylated-deoxyhexoses traverse common early biosynthetic steps as nucleotide-monosaccharides. As a prelude to a full biosynthetic characterization, we present herein the results from bioinformatics-based, proteomics-supported predictions of the pathway for virenose synthesis. Alternative possibilities are considered which include both GDP-mannose and TDP-glucose as precursors. CONCLUSION We propose that biosynthesis of the unique C. burnetii biomarker, virenose, involves an early pathway similar to that of other C-3'-methylated deoxysugars which then diverges depending upon the nucleotide-carrier involved. The alternatives yield either the D- or L-enantiomers of virenose. Both pathways require five enzymatic steps, beginning with either glucose-6-phosphate or mannose-6-phosphate. Our in silico results comprise a model for virenose biosynthesis that can be directly tested. Definition of this pathway should facilitate the development of therapeutic agents useful for treatment of Q fever, as well as allowing improvements in the methods for diagnosing this highly infectious disease.
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Affiliation(s)
- Gabriela Flores-Ramirez
- Department of Rickettsiology, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta, 9, Bratislava, 845 05, Slovakia
| | - Stefan Janecek
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, 845 51, Slovakia
| | - Ján A Miernyk
- USDA, Agricultural Research Service, Plant Genetics Research Unit, Columbia, MO, 65211, USA
- Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA
- Department of Biochemistry, University of Missouri, Columbia, MO, 65211, USA
| | - Ludovit Skultety
- Department of Rickettsiology, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta, 9, Bratislava, 845 05, Slovakia
- Centre for Molecular Medicine, Slovak Academy of Sciences, Bratislava, 831 01, Slovakia
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Núñez LE, Nybo SE, González-Sabín J, Pérez M, Menéndez N, Braña AF, Shaaban KA, He M, Morís F, Salas JA, Rohr J, Méndez C. A novel mithramycin analogue with high antitumor activity and less toxicity generated by combinatorial biosynthesis. J Med Chem 2012; 55:5813-25. [PMID: 22578073 DOI: 10.1021/jm300234t] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mithramycin is an antitumor compound produced by Streptomyces argillaceus that has been used for the treatment of several types of tumors and hypercalcaemia processes. However, its use in humans has been limited because of its side effects. Using combinatorial biosynthesis approaches, we have generated seven new mithramycin derivatives, which differ from the parental compound in the sugar profile or in both the sugar profile and the 3-side chain. From these studies three novel derivatives were identified, demycarosyl-3D-β-d-digitoxosylmithramycin SK, demycarosylmithramycin SDK, and demycarosyl-3D-β-d-digitoxosylmithramycin SDK, which show high antitumor activity. The first one, which combines two structural features previously found to improve pharmacological behavior, was generated following two different strategies, and it showed less toxicity than mithramycin. Preliminary in vivo evaluation of its antitumor activity through hollow fiber assays, and in subcutaneous colon and melanoma cancers xenografts models, suggests that demycarosyl-3D-β-d-digitoxosylmithramycin SK could be a promising antitumor agent worthy of further investigation.
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Affiliation(s)
- Luz E Núñez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain
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Wang G, Kharel MK, Pahari P, Rohr J. Investigating Mithramycin deoxysugar biosynthesis: enzymatic total synthesis of TDP-D-olivose. Chembiochem 2011; 12:2568-71. [PMID: 21960454 PMCID: PMC3412565 DOI: 10.1002/cbic.201100540] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Indexed: 02/04/2023]
Abstract
Mix'n'match: Enzymatic total synthesis of TDP-D-olivose was achieved, starting from TDP-4-keto-6-deoxy-D-glucose, by combining three pathway enzymes with one cofactor-regenerating enzyme. The results also revealed that MtmC is a bifunctional enzyme that can perform a 4-ketoreduction necessary for D-olivose biosynthesis besides the previously found C-methyltransfer for D-mycarose biosynthesis.
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Affiliation(s)
- Guojun Wang
- Dr. G. Wang, Prof. Dr. M. K. Kharel, Dr. P. Pahari, Prof. Dr. J. Rohr Department of Pharmaceutical Sciences, University of Kentucky 789 South Limestone Street, Lexington, KY 40536-0596 (USA)
| | - Madan K. Kharel
- Dr. G. Wang, Prof. Dr. M. K. Kharel, Dr. P. Pahari, Prof. Dr. J. Rohr Department of Pharmaceutical Sciences, University of Kentucky 789 South Limestone Street, Lexington, KY 40536-0596 (USA)
- Prof. Dr. M. K. Kharel Present address: Midway College School of Pharmacy 120 Scott Perry Drive, Paintsville, KY 41240 (USA)
| | - Pallab Pahari
- Dr. G. Wang, Prof. Dr. M. K. Kharel, Dr. P. Pahari, Prof. Dr. J. Rohr Department of Pharmaceutical Sciences, University of Kentucky 789 South Limestone Street, Lexington, KY 40536-0596 (USA)
| | - Jürgen Rohr
- Dr. G. Wang, Prof. Dr. M. K. Kharel, Dr. P. Pahari, Prof. Dr. J. Rohr Department of Pharmaceutical Sciences, University of Kentucky 789 South Limestone Street, Lexington, KY 40536-0596 (USA)
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14
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Abstract
Many bioactive compounds contain as part of their molecules one or more deoxysugar units. Their presence in the final compound is generally necessary for biological activity. These sugars derive from common monosaccharides, like d-glucose, which have lost one or more hydroxyl groups (monodeoxysugars, dideoxysugars, trideoxysugars) during their biosynthesis. These deoxysugars are transferred to the final molecule by the action of a glycosyltransferase. Here, we first summarize the different biosynthetic steps required for the generation of the different families of deoxysugars, including those containing extra methyl or amino groups, or tailoring modifications of the glycosylated compounds. We then give examples of several strategies for modification of the glycosylation pattern of a given bioactive compound: inactivation of genes involved in the biosynthesis of deoxysugars; heterologous expression of genes for the biosynthesis or transfer of a specific deoxysugar; and combinatorial biosynthesis (including the use of gene cassette plasmids). Finally, we report techniques for the isolation and detection of the new glycosylated derivatives generated using these strategies.
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Affiliation(s)
- Felipe Lombó
- Departamento de Biología Funcional and Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
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15
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Liu T, Kharel MK, Zhu L, Bright SA, Mattingly C, Adams VR, Rohr J. Inactivation of the ketoreductase gilU gene of the gilvocarcin biosynthetic gene cluster yields new analogues with partly improved biological activity. Chembiochem 2009; 10:278-86. [PMID: 19067453 DOI: 10.1002/cbic.200800348] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Four new analogues of the gilvocarcin-type aryl-C-glycoside antitumor compounds, namely 4'-hydroxy gilvocarcin V (4'-OH-GV), 4'-hydroxy gilvocarcin M, 4'-hydroxy gilvocarcin E and 12-demethyl-defucogilvocarcin V, were produced through inactivation of the gilU gene. The 4'-OH-analogues showed improved activity against lung cancer cell lines as compared to their parent compounds without 4'-OH group (gilvocarcins V and E). The structures of the sugar-containing new mutant products indicate that the enzyme GilU acts as an unusual ketoreductase involved in the biosynthesis of the C-glycosidically linked deoxysugar moiety of the gilvocarcins. The structures of the new gilvocarcins indicate substrate flexibility of the post-polyketide synthase modifying enzymes, particularly the C-glycosyltransferase and the enzyme responsible for the sugar ring contraction. The results also shed light into biosynthetic sequence of events in the late steps of biosynthetic pathway of gilvocarcin V.
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Affiliation(s)
- Tao Liu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536-0082, USA
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16
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Olano C, Méndez C, Salas JA. Antitumor compounds from actinomycetes: from gene clusters to new derivatives by combinatorial biosynthesis. Nat Prod Rep 2009; 26:628-60. [PMID: 19387499 DOI: 10.1039/b822528a] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Covering: up to October 2008. Antitumor compounds produced by actinomycetes and novel derivatives generated by combinatorial biosynthesis are reviewed (with 318 references cited.) The different structural groups for which the relevant gene clusters have been isolated and characterized are reviewed, with a description of the strategies used for the generation of the novel derivatives and the activities of these compounds against tumor cell lines.
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Affiliation(s)
- Carlos Olano
- Departamento de Biología Funcional and Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A.), Universidad de Oviedo, 33006, Oviedo, Spain
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17
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Zhao P, Ueda JY, Kozone I, Chijiwa S, Takagi M, Kudo F, Nishiyama M, Shin-ya K, Kuzuyama T. New glycosylated derivatives of versipelostatin, the GRP78/Bip molecular chaperone down-regulator, from Streptomyces versipellis 4083-SVS6. Org Biomol Chem 2009; 7:1454-60. [PMID: 19300832 DOI: 10.1039/b817312e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four novel glycosylated derivatives of versipelostatin (1), versipelostatins B-E (2-5), were isolated from the culture broth of Streptomyces versipellis 4083-SVS6. The inhibitory activities of the isolated compounds against the expression of molecular chaperone GRP78 induced by 2-deoxyglucose were evaluated. Of the five versipelostatin family members, 1 and 4 were the more potent with IC(50) values of 3.5 and 4.3 microM. These results suggest that the alpha-L-oleandropyranosyl (1-->4)-beta-D-digitoxopyranosyl residue in the sugar moiety may play an important role in down-regulating GRP78 expression induced by 2-deoxyglucose.
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Affiliation(s)
- Ping Zhao
- Laboratory of Cell Biotechnology, Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-8657, Japan
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18
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Pérez M, Baig I, Braña AF, Salas JA, Rohr J, Méndez C. Generation of new derivatives of the antitumor antibiotic mithramycin by altering the glycosylation pattern through combinatorial biosynthesis. Chembiochem 2009; 9:2295-304. [PMID: 18756551 DOI: 10.1002/cbic.200800299] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mithramycin is an antitumor drug produced by Streptomyces argillaceus. It consists of a tricyclic aglycone and five deoxyhexoses that form a disaccharide and a trisaccharide chain, which are important for target interaction and therefore for the antitumor activity. Using a combinatorial biosynthesis approach, we have generated nine mithramycin derivatives, seven of which are new compounds, with alterations in the glycosylation pattern. The wild-type S. argillaceus strain and the mutant S. argillaceus M7U1, which has altered D-oliose biosynthesis, were used as hosts to express various "sugar plasmids", each one directing the biosynthesis of a different deoxyhexose. The newly formed compounds were purified and characterized by MS and NMR. Compared to mithramycin, they contained different sugar substitutions in the second (D-olivose, D-mycarose, or D-boivinose instead of D-oliose) and third (D-digitoxose instead of D-mycarose) sugar units of the trisaccharide as well as in the first (D-amicetose instead of D-olivose) sugar unit of the disaccharide. All compounds showed antitumor activity against different tumor cell lines. Structure-activity relationships are discussed on the basis of the number and type of deoxyhexoses present in these mithramycin derivatives.
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Affiliation(s)
- María Pérez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Spain
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19
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Thibodeaux C, Melançon C, Liu HW. Biosynthese von Naturstoffzuckern und enzymatische Glycodiversifizierung. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801204] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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20
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Thibodeaux CJ, Melançon CE, Liu HW. Natural-product sugar biosynthesis and enzymatic glycodiversification. Angew Chem Int Ed Engl 2008; 47:9814-59. [PMID: 19058170 PMCID: PMC2796923 DOI: 10.1002/anie.200801204] [Citation(s) in RCA: 320] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Many biologically active small-molecule natural products produced by microorganisms derive their activities from sugar substituents. Changing the structures of these sugars can have a profound impact on the biological properties of the parent compounds. This realization has inspired attempts to derivatize the sugar moieties of these natural products through exploitation of the sugar biosynthetic machinery. This approach requires an understanding of the biosynthetic pathway of each target sugar and detailed mechanistic knowledge of the key enzymes. Scientists have begun to unravel the biosynthetic logic behind the assembly of many glycosylated natural products and have found that a core set of enzyme activities is mixed and matched to synthesize the diverse sugar structures observed in nature. Remarkably, many of these sugar biosynthetic enzymes and glycosyltransferases also exhibit relaxed substrate specificity. The promiscuity of these enzymes has prompted efforts to modify the sugar structures and alter the glycosylation patterns of natural products through metabolic pathway engineering and enzymatic glycodiversification. In applied biomedical research, these studies will enable the development of new glycosylation tools and generate novel glycoforms of secondary metabolites with useful biological activity.
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Affiliation(s)
- Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Charles E. Melançon
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
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21
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Van Lanen SG, Oh TJ, Liu W, Wendt-Pienkowski E, Shen B. Characterization of the maduropeptin biosynthetic gene cluster from Actinomadura madurae ATCC 39144 supporting a unifying paradigm for enediyne biosynthesis. J Am Chem Soc 2007; 129:13082-94. [PMID: 17918933 PMCID: PMC2529154 DOI: 10.1021/ja073275o] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biosynthetic gene cluster for the enediyne antitumor antibiotic maduropeptin (MDP) from Actinomadura madurae ATCC 39144 was cloned and sequenced. Cloning of the mdp gene cluster was confirmed by heterologous complementation of enediyne polyketide synthase (PKS) mutants from the C-1027 producer Streptomyces globisporus and the neocarzinostatin producer Streptomyces carzinostaticus using the MDP enediyne PKS and associated genes. Furthermore, MDP was produced, and its apoprotein was isolated and N-terminal sequenced; the encoding gene, mdpA, was found to reside within the cluster. The biosynthesis of MDP is highlighted by two iterative type I PKSs--the enediyne PKS and a 6-methylsalicylic acid PKS; generation of (S)-3-(2-chloro-3-hydroxy-4-methoxyphenyl)-3-hydroxypropionic acid derived from L-alpha-tyrosine; a unique type of enediyne apoprotein; and a convergent biosynthetic approach to the final MDP chromophore. The results demonstrate a platform for engineering new enediynes by combinatorial biosynthesis and establish a unified paradigm for the biosynthesis of enediyne polyketides.
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Affiliation(s)
| | | | - Wen Liu
- Division of Pharmaceutical Sciences
| | | | - Ben Shen
- Division of Pharmaceutical Sciences
- University of Wisconsin National Cooperative Drug Discovery Group
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53705
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22
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Menéndez N, Braña AF, Salas JA, Méndez C. Involvement of a chromomycin ABC transporter system in secretion of a deacetylated precursor during chromomycin biosynthesis. Microbiology (Reading) 2007; 153:3061-3070. [PMID: 17768249 DOI: 10.1099/mic.0.2007/007922-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromomycin A(3) is an antitumour antibiotic that acts by inhibiting transcription and replication of DNA. The producer micro-organism Streptomyces griseus subsp. griseus is highly resistant to chromomycin A(3) and to the structurally related compound mithramycin upon induction with chromomycin A(3). The biosynthetic gene cluster of chromomycin contains three genes involved in self-resistance to chromomycin in S. griseus: cmrA and cmrB encode a type I ATP-binding cassette (ABC) transporter, and cmrX encodes a UvrA-like protein of ABC excision nuclease systems. These genes are linked in the chromosome, together with a gene encoding a transcriptional repressor (cmmRII). Involvement of these genes in chromomycin resistance was determined through gene inactivation, and heterologous expression in Streptomyces albus. Inactivation of cmrX produced a chromomycin-sensitive low-producer strain, while inactivation of cmmRII generated a high-chromomycin-producer strain, which was resistant to chromomycin, and also to mithramycin. Expression of either cmrA and cmrB, or cmrX, in S. albus generated strains with low chromomycin resistance; it was therefore necessary to co-express the three genes to achieve high levels of resistance. However, the CmrAB ABC transporter conferred a high level of resistance to the biosynthesis intermediate 4A,4E-O-dideacetyl-chromomycin A(3). A model is proposed for the biosynthesis of, and self-resistance to, chromomycin A(3) in S. griseus subsp. griseus.
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Affiliation(s)
- Nuria Menéndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Spain
| | - Alfredo F Braña
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Spain
| | - José A Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Spain
| | - Carmen Méndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Spain
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23
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Pérez M, Lombó F, Baig I, Braña AF, Rohr J, Salas JA, Méndez C. Combinatorial biosynthesis of antitumor deoxysugar pathways in Streptomyces griseus: Reconstitution of "unnatural natural gene clusters" for the biosynthesis of four 2,6-D-dideoxyhexoses. Appl Environ Microbiol 2006; 72:6644-52. [PMID: 17021216 PMCID: PMC1610316 DOI: 10.1128/aem.01266-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Combinatorial biosynthesis was applied to Streptomyces deoxysugar biosynthesis genes in order to reconstitute "unnatural natural gene clusters" for the biosynthesis of four D-deoxysugars (D-olivose, D-oliose, D-digitoxose, and D-boivinose). Expression of these gene clusters in Streptomyces albus 16F4 was used to prove the functionality of the designed clusters through the generation of glycosylated tetracenomycins. Three glycosylated tetracenomycins were generated and characterized, two of which (D-digitoxosyl-tetracenomycin C and D-boivinosyl-tetracenocmycin C) were novel compounds. The constructed gene clusters may be used to increase the capabilities of microorganisms to synthesize new deoxysugars and therefore to produce new glycosylated bioactive compounds.
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Affiliation(s)
- María Pérez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
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24
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Lombó F, Menéndez N, Salas JA, Méndez C. The aureolic acid family of antitumor compounds: structure, mode of action, biosynthesis, and novel derivatives. Appl Microbiol Biotechnol 2006; 73:1-14. [PMID: 17013601 DOI: 10.1007/s00253-006-0511-6] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 05/15/2006] [Accepted: 05/16/2006] [Indexed: 10/24/2022]
Abstract
Members of the aureolic acid family are tricyclic polyketides with antitumor activity which are produced by different streptomycete species. These members are glycosylated compounds with two oligosaccharide chains of variable sugar length. They interact with the DNA minor groove in high-GC-content regions in a nonintercalative way and with a requirement for magnesium ions. Mithramycin and chromomycins are the most representative members of the family, mithramycin being used as a chemotherapeutic agent for the treatment of several cancer diseases. For chromomycin and durhamycin A, antiviral activity has also been reported. The biosynthesis gene clusters for mithramycin and chromomycin A(3) have been studied in detail by gene sequencing, insertional inactivation, and gene expression. Most of the biosynthetic intermediates in these pathways have been isolated and characterized. Some of these compounds showed an increase in antitumor activity in comparison with the parent compounds. A common step in the biosynthesis of all members of the family is the formation of the tetracyclic intermediate premithramycinone. Further biosynthetic steps (glycosylation, methylations, acylations) proceed through tetracyclic intermediates which are finally converted into tricyclic compounds by the action of a monooxygenase, a key event for the biological activity. Heterologous expression of biosynthetic genes from other aromatic polyketide pathways in the mithramycin producer (or some mutants) led to the isolation of novel hybrid compounds.
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Affiliation(s)
- Felipe Lombó
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006, Oviedo, Spain
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25
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Jia XY, Tian ZH, Shao L, Qu XD, Zhao QF, Tang J, Tang GL, Liu W. Genetic Characterization of the Chlorothricin Gene Cluster as a Model for Spirotetronate Antibiotic Biosynthesis. ACTA ACUST UNITED AC 2006; 13:575-85. [PMID: 16793515 DOI: 10.1016/j.chembiol.2006.03.008] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 03/16/2006] [Accepted: 03/27/2006] [Indexed: 11/15/2022]
Abstract
The biosynthetic gene cluster for chlorothricin (CHL) was localized to a 122 kb contiguous DNA from Streptomyces antibioticus DSM 40725, and its involvement in CHL biosynthesis was confirmed by gene inactivation and complementation. Bioinformatic analysis of the sequenced 111.989 kb DNA region revealed 42 open reading frames, 35 of which were defined to constitute the CHL gene cluster. An assembly model for CHL biosynthesis from D-olivose, 2-methoxy-5-chloro-6-methylsalicyclic acid, and chlorothricolide building blocks was proposed. This work represents cloning of a gene cluster for spirotetronate antibiotic biosynthesis and sets the stage to investigate the unusual macrolide biosynthesis including tandem Diels-Alder cyclizations, Baeyer-Villiger oxidation, and incorporation of an enoylpyruvate unit.
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Affiliation(s)
- Xin-Ying Jia
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai, 200032, China
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26
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Salas JA, Méndez C. Biosynthesis Pathways for Deoxysugars in Antibiotic-Producing Actinomycetes: Isolation, Characterization and Generation of Novel Glycosylated Derivatives. J Mol Microbiol Biotechnol 2005; 9:77-85. [PMID: 16319497 DOI: 10.1159/000088838] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many bioactive natural products synthesized by actinomycetes are glycosylated compounds in which the appended sugars contribute to specific interactions with their biological target. Most of these sugars are 6-deoxyhexoses, of which more than 70 different forms have been identified, and an increasing number of gene clusters involved in 6-deoxyhexoses biosynthesis are being characterized from antibiotic-producing actinomycetes. Novel glycosylated compounds have been generated by modifying natural deoxysugar biosynthesis pathways in the producer organisms, and/or the simultaneous expression in these strains of selected deoxysugar biosynthesis genes from other strains. Non-producing strains endowed with the capacity to synthesize novel deoxysugars through the expression of engineered deoxysugar biosynthesis clusters can also be used as alternative hosts. Transfer of these deoxysugars to a multiplicity of aglycones relies upon the existence of glycosyltransferases with an inherent degree of 'relaxed substrate specificity'. In this review, we analyze how the knowledge coming out from isolation and characterization of deoxysugar biosynthesis pathways from actinomycetes is being used to produce novel glycosylated derivatives of natural products.
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Affiliation(s)
- José A Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Spain.
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27
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Nur-e-Alam M, Méndez C, Salas JA, Rohr J. Elucidation of the glycosylation sequence of mithramycin biosynthesis: isolation of 3A-deolivosylpremithramycin B and its conversion to premithramycin B by glycosyltransferase MtmGII. Chembiochem 2005; 6:632-6. [PMID: 15712316 DOI: 10.1002/cbic.200400309] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mohammad Nur-e-Alam
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536-0082, USA
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28
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Méndez C, Salas JA. Engineering glycosylation in bioactive compounds by combinatorial biosynthesis. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2005:127-46. [PMID: 15645719 DOI: 10.1007/3-540-27055-8_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- C Méndez
- Departamento de Biologia Funcional e Instituto Universitario de Oncologia (I.U.O.P.A.), Universidad de Oviedo, Spain
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29
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Lombó F, Gibson M, Greenwell L, Braña AF, Rohr J, Salas JA, Méndez C. Engineering Biosynthetic Pathways for Deoxysugars: Branched-Chain Sugar Pathways and Derivatives from the Antitumor Tetracenomycin. ACTA ACUST UNITED AC 2004; 11:1709-18. [PMID: 15610855 DOI: 10.1016/j.chembiol.2004.10.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 10/04/2004] [Accepted: 10/07/2004] [Indexed: 10/26/2022]
Abstract
Sugar biosynthesis cassette genes have been used to construct plasmids directing the biosynthesis of branched-chain deoxysugars: pFL942 (NDP-L-mycarose), pFL947 (NDP-4-deacetyl-L-chromose B), and pFL946/pFL954 (NDP-2,3,4-tridemethyl-L-nogalose). Expression of pFL942 and pFL947 in S. lividans 16F4, which harbors genes for elloramycinone biosynthesis and the flexible ElmGT glycosyltransferase of the elloramycin biosynthetic pathway, led to the formation of two compounds: 8-alpha-L-mycarosyl-elloramycinone and 8-demethyl-8-(4-deacetyl)-alpha-L-chromosyl-tetracenomycin C, respectively. Expression of pFL946 or pFL954 failed to produce detectable amounts of a novel glycosylated tetracenomycin derivative. Formation of these two compounds represents examples of the sugar cosubstrate flexibility of the ElmGT glycosyltransferase. The use of these cassette plasmids also provided insights into the substrate flexibility of deoxysugar biosynthesis enzymes as the C-methyltransferases EryBIII and MtmC, the epimerases OleL and EryBVII, and the 4-ketoreductases EryBIV and OleU.
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Affiliation(s)
- Felipe Lombó
- Departamento de Biología Funcional and Instituto Universitario de Oncología, del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain
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30
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Bruheim P, Borgos SEF, Tsan P, Sletta H, Ellingsen TE, Lancelin JM, Zotchev SB. Chemical diversity of polyene macrolides produced by Streptomyces noursei ATCC 11455 and recombinant strain ERD44 with genetically altered polyketide synthase NysC. Antimicrob Agents Chemother 2004; 48:4120-9. [PMID: 15504830 PMCID: PMC525400 DOI: 10.1128/aac.48.11.4120-4129.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 03/29/2004] [Accepted: 07/11/2004] [Indexed: 11/20/2022] Open
Abstract
The gram-positive bacterium Streptomyces noursei ATCC 11455 produces a complex mixture of polyene macrolides generally termed nystatins. Although the structures for nystatins A(1) and A(3) have been reported, the identities of other components of the nystatin complex remain obscure. Analyses of the culture extract from the S. noursei wild type revealed the presence of several nystatin-related compounds for which chemical structures could be suggested on the basis of their molecular weights, their UV spectra, and knowledge of the nystatin biosynthetic pathway. Nuclear magnetic resonance (NMR) studies with one of these polyene macrolides identified it as a nystatin analogue containing a mycarose moiety at C-35. A similar investigation was performed with the culture extract of the ERD44 mutant, which has a genetically altered polyketide synthase (PKS) NysC and which was previously shown to produce a heptaene nystatin analogue. The latter compound, tentatively named S44HP, and its derivative, which contains two deoxysugar moieties, were purified; and their structures were confirmed by NMR analysis. Nystatin analogues with an expanded macrolactone ring were also observed in the extract of the ERD44 mutant, suggesting that the altered PKS can "stutter" during the polyketide chain assembly. These data provide new insights into the biosynthesis of polyene macrolide antibiotics and the functionalities of PKSs and post-PKS modification enzymes.
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Affiliation(s)
- Per Bruheim
- Department of Biotechnology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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Menéndez N, Nur-E-Alam M, Braña AF, Rohr J, Salas JA, Méndez C. Tailoring modification of deoxysugars during biosynthesis of the antitumour drug chromomycin A by Streptomyces griseus ssp. griseus. Mol Microbiol 2004; 53:903-15. [PMID: 15255901 DOI: 10.1111/j.1365-2958.2004.04166.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Chromomycin A3 is a member of the aureolic acid group family of antitumour drugs. Three tailoring modification steps occur during its biosynthesis affecting the sugar moieties: two O-acetylations and one O-methylation. The 4-O-methylation in the 4-O-methyl-D-oliose moiety of the disaccharide chain is catalysed by the cmmMIII gene product. Inactivation of this gene generated a chromomycin-non-producing mutant that accumulated three unmethylated derivatives containing all sugars but differing in the acylation pattern. Two of these compounds were shown to be substrates of the methyltransferase as determined by their bioconversion into chromomycin A2 and A3 after feeding these compounds to a Streptomyces albus strain expressing the cmmMIII gene. The same single membrane-bound enzyme, encoded by the cmmA gene, is responsible for both acetyl transfer reactions, which convert a relatively inactive compound into the bioactive chromomycin A3. Insertional inactivation of this gene resulted in a mutant accumulating a dideacetylated chromomycin A3 derivative. This compound, lacking both acetyl groups, was converted in a two-step reaction via the 4E-monoacetylated intermediate into chromomycin A3 when fed to cultures of S. albus expressing the cmmA gene. This acetylation step would occur as the last step in chromomycin biosynthesis, being a very important event for self-protection of the producing organism. It would convert a molecule with low biological activity into an active one, in a reaction catalysed by an enzyme that is predicted to be located in the cell membrane.
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Affiliation(s)
- Nuria Menéndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
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Remsing LL, González AM, Nur-e-Alam M, Fernández-Lozano MJ, Braña AF, Rix U, Oliveira MA, Méndez C, Salas JA, Rohr J. Mithramycin SK, a novel antitumor drug with improved therapeutic index, mithramycin SA, and demycarosyl-mithramycin SK: three new products generated in the mithramycin producer Streptomyces argillaceus through combinatorial biosynthesis. J Am Chem Soc 2003; 125:5745-53. [PMID: 12733914 PMCID: PMC4480629 DOI: 10.1021/ja034162h] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To gain initial structure-activity relationships regarding the highly functionalized pentyl side chain attached at C-3 of mithramycin (MTM), we focused on a post-polyketide synthase (post-PKS) tailoring step of the MTM biosynthesis by Streptomyces argillaceus ATCC 12956, which was proposed to be catalyzed by ketoreductase (KR) MtmW. In this last step of the MTM biosynthesis, a keto group of the pentyl side chain is reduced to a secondary alcohol, and we anticipated the generation of an MTM derivative with an additional keto group in the 3-side chain. Insertional inactivation of mtmW, a gene located ca. 8 kb downstream of the mithramycin-PKS genes, yielded an S. argillaceus mutant, which accumulated three new mithramycin analogues, namely mithramycin SA, demycarosyl-mithramycin SK, and mithramycin SK (MTM-SK). The structures of these three compounds confirmed indirectly the proposed role of MtmW in MTM biosynthesis. However, the new mithramycin derivatives bear unexpectedly shorter 3-side chains (ethyl or butyl) than MTM, presumably caused by nonenzymatic rearrangement or cleavage reactions of the initially formed pentyl side chain with a reactive beta-dicarbonyl functional group. The major product, MTM-SK, was tested in vitro against a variety of human cancer cell lines, as well as in an in vitro toxicity assay, and showed an improved therapeutic index, in comparison to the parent drug, MTM.
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Abstract
Polyketides are a large class of structurally diverse, biologically active natural products. Recent experiments add evidence that many of the enzymes involved in the biosynthesis of these natural products are intrinsically tolerant of nonnatural substrates. In addition, an increasing understanding of structure-function relationships in various enzyme-substrate systems is aiding efforts to begin engineering these proteins for even greater synthetic utility.
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Affiliation(s)
- Nicola L Pohl
- Department of Chemistry and the Plant Sciences Institute, 2756 Gilman Hall, Iowa State University, Ames, IA 50011-3111, USA.
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Li SM, Westrich L, Schmidt J, Kuhnt C, Heide L. Methyltransferase genes in Streptomyces rishiriensis: new coumermycin derivatives from gene-inactivation experiments. MICROBIOLOGY (READING, ENGLAND) 2002; 148:3317-3326. [PMID: 12368465 DOI: 10.1099/00221287-148-10-3317] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The coumarin antibiotic coumermycin A(1) contains at least eight methyl groups, presumably derived from S-adenosylmethionine. Two putative methyltransferase genes, couO and couP, of the coumermycin A(1) biosynthetic gene cluster were inactivated by in-frame deletion. In the resulting mutants, coumermycin A(1) production was abolished. New coumermycin derivatives were accumulated instead, and were identified by HPLC-MS using selected reaction monitoring via electrospray ionization. couO mutants accumulated a coumermycin derivative lacking the methyl groups at C-8 of the characteristic aminocoumarin rings, whereas in the couP mutant a coumermycin derivative lacking the methyl groups at the 4-hydroxyl groups of the two deoxysugar moieties was identified. These results provided evidence that couO encodes a C-methyltransferase responsible for the transfer of a methyl group to C-8 of the aminocoumarin ring, and couP an O-methyltransferase for methylation of 4-OH of the sugar in the biosynthesis of coumermycin A(1), respectively. C-methylation of the aminocoumarin ring is considered as an early step of coumermycin biosynthesis. Nevertheless, the intermediates with the non-methylated aminocoumarin ring were accepted by the enzymes catalysing the subsequent steps of the pathway. The new, demethylated secondary metabolites were produced in an amount at least as high as that of coumermycin A(1) in the wild-type.
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Affiliation(s)
- Shu-Ming Li
- Eberhard-Karls-Universität Tübingen, Pharmazeutische Biologie, Auf der Morgenstelle 8,D-72076 Tübingen, Germany1
| | - Lucia Westrich
- Eberhard-Karls-Universität Tübingen, Pharmazeutische Biologie, Auf der Morgenstelle 8,D-72076 Tübingen, Germany1
| | - Jürgen Schmidt
- Institut für Pflanzenbiochemie, Weinberg 3, 06120 Halle (Saale), Germany2
| | - Christine Kuhnt
- Institut für Pflanzenbiochemie, Weinberg 3, 06120 Halle (Saale), Germany2
| | - Lutz Heide
- Eberhard-Karls-Universität Tübingen, Pharmazeutische Biologie, Auf der Morgenstelle 8,D-72076 Tübingen, Germany1
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Rodríguez L, Aguirrezabalaga I, Allende N, Braña AF, Méndez C, Salas JA. Engineering deoxysugar biosynthetic pathways from antibiotic-producing microorganisms. A tool to produce novel glycosylated bioactive compounds. CHEMISTRY & BIOLOGY 2002; 9:721-9. [PMID: 12079784 DOI: 10.1016/s1074-5521(02)00154-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A plasmid (pLN2) was generated in which genes involved in the biosynthesis of L-oleandrose in the oleandomycin producer Streptomyces antibioticus ATCC11891 were cloned. pLN2 was used to direct the biosynthesis of different deoxysugars by exchanging and/or adding genes from other antibiotic biosynthetic clusters. Transfer of the synthesized deoxysugars to the tetracenomycin C aglycon, 8-demethyl-tetracenomycin C, through the use of the "sugar flexible" glycosyltransferase ElmGT, validated the system. Several pLN2 derivatives were constructed by replacement of the oleU 4-ketoreductase gene by different 4-ketoreductase genes. Some of them, such as EryBIV and UrdR, reduced the keto group of the 4-keto intermediates, generating L-olivosyl and D-olivosyl derivatives, respectively. The system was also used to generate an L-rhamnosyl derivative (through a two-gene deletion) and an L-rhodinosyl derivative (through a combination of a gene replacement and a gene addition).
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Affiliation(s)
- Leticia Rodríguez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, 33006, Oviedo, Spain
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Trefzer A, Blanco G, Remsing L, Künzel E, Rix U, Lipata F, Braña AF, Méndez C, Rohr J, Bechthold A, Salas JA. Rationally designed glycosylated premithramycins: hybrid aromatic polyketides using genes from three different biosynthetic pathways. J Am Chem Soc 2002; 124:6056-62. [PMID: 12022840 DOI: 10.1021/ja017385l] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Heterologous expression of the urdGT2 gene from the urdamycin producer Streptomyces fradiae Tü2717, which encodes a C-glycosyltransferase, into mutants of the mithramycin producer Streptomyces argillaceus, in which either one or all glycosyltransferases were inactivated, yielded four novel C-glycosylated premithramycin-type molecules. Structure elucidation revealed these to be 9-C-olivosylpremithramycinone, 9-C-mycarosylpremithramycinone, and their respective 4-O-demethyl analogues. In another experiment, both the urdGT2 gene from S. fradiae and the lanGT1 gene from S. cyanogenus, were coexpressed into a S. argillaceus mutant lacking the MtmGIV glycosyltransferase. This experiment, in which genes from three different organisms were combined, resulted in the production of 9-C-(olivo-1-4-olivosyl)premithramycinone. These results prove the unique substrate flexibility of the C-glycosyltransferase UrdGT2, which tolerates not only a variety of sugar-donor substrates, but also various acceptor substrates. The five new hybrid products also represent the first compounds, in which sugars were attached to a position that is normally unglycosylated. The successful combination of two glycosyltransferases in the latter experiment proves that the design of saccharide side chains by combinatorial biosynthetic methods is possible.
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Affiliation(s)
- Axel Trefzer
- Albert-Ludwigs-Universität Freiburg im Breisgau, Pharmazeutische Biologie, Stefan-Meier Strasse 19, 79104 Freiburg, Germany
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Remsing LL, Garcia-Bernardo J, Gonzalez A, Künzel E, Rix U, Braña AF, Bearden DW, Méndez C, Salas JA, Rohr J. Ketopremithramycins and ketomithramycins, four new aureolic acid-type compounds obtained upon inactivation of two genes involved in the biosynthesis of the deoxysugar moieties of the antitumor drug mithramycin by Streptomyces argillaceus, reveal novel insights into post-PKS tailoring steps of the mithramycin biosynthetic pathway. J Am Chem Soc 2002; 124:1606-14. [PMID: 11853433 PMCID: PMC4480631 DOI: 10.1021/ja0105156] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mithramycin is an aureolic acid-type antimicrobial and antitumor agent produced by Streptomyces argillaceus. Modifying post-polyketide synthase (PKS) tailoring enzymes involved in the production of mithramycin is an effective way of gaining further information regarding the late steps of its biosynthetic pathway. In addition, new "unnatural" natural products of the aureolic acid-type class are likely to be produced. The role of two such post-PKS tailoring enzymes, encoded by mtmC and mtmTIII, was investigated, and four novel aureolic acid class drugs, two premithramycin-type molecules and two mithramycin derivatives, were isolated from mutant strains constructed by insertional gene inactivation of either of these two genes. From data bank comparisons, the corresponding proteins MtmC and MtmTIII were believed to act as a C-methyltransferase involved in the production of the D-mycarose (sugar E) of mithramycin and as a ketoreductase seemingly involved in the biosynthesis of the mithramycin aglycon, respectively. However, gene inactivation and analysis of the accumulated products revealed that both genes encode enzymes participating in the biosynthesis of the D-mycarose building block. Furthermore, the inactivation of MtmC seems to affect the ketoreductase responsible for 4-ketoreduction of sugar C, a D-olivose. Instead of obtaining premithramycin and mithramycin derivatives with a modified E-sugar upon inactivation of mtmC, compounds were obtained that completely lack the E-sugar moiety and that possess an unexpected 4-ketosugar moiety instead of the D-olivose at the beginning of the lower deoxysaccharide chain. The inactivation of mtmTIII led to the accumulation of 4E-ketomithramycin, showing that this ketoreductase is responsible for the 4-ketoreduction of the D-mycarose moiety. The new compounds of the mutant strains, 4A-ketopremithramycin A2, 4A-keto-9-demethylpremithramycin A2, 4C-keto-demycarosylmithramycin, and 4E-ketomithramycin, indicate surprising substrate flexibility of post-PKS enzymes of the mithramycin biosynthetic pathway. Although the glycosyltransferase responsible for the attachment of D-mycarose cannot transfer the unmethylated sugar to the existing lower disaccharide chain, it can transfer the 4-ketoform of sugar E. In addition, the glycosyltransferase MtmGIV, which is responsible for the linkage of sugar C, is also able to transfer an activated 4-ketosugar. The oxygenase MtmOIV, normally responsible for the oxidative cleavage of the tetracyclic premithramycin B into the tricyclic immediate precursor of mithramycin, can act on a substrate analogue with a modified or even incomplete trisaccharide chain. The same is true for glycosyltransferases MtmGI and MtmGII, both of which partake in the formation and attachment of the A-B disaccharide in mithramycin.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Jose A. Salas
- To whom correspondence should be addressed. Tel: (843) 876 5091. Fax: (843) 792 0759. J.R., ; J.A.S.,
| | - Jürgen Rohr
- To whom correspondence should be addressed. Tel: (843) 876 5091. Fax: (843) 792 0759. J.R., ; J.A.S.,
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Abstract
Many bioactive natural products are glycosylated compounds in which the sugars are important or essential for biological activity. The isolation of several sugar biosynthesis gene clusters and glycosyltransferases from different antibiotic-producing organisms, and the increasing knowledge about these biosynthetic pathways opens up the possibility of generating novel bioactive compounds through combinatorial biosynthesis in the near future. Recent advances in this area indicate that antibiotic glycosyltransferases show some substrate flexibility that might allow us to alter the types of sugar transferred to the different aglycons or, less frequently, to change the position of its attachment.
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Affiliation(s)
- C Méndez
- Dept Biologia Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
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