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Abstract
The novel or designer metabolites produced by fungal endophytes are increasingly recognized by natural chemists due to their diverse structures and as candidates for drug discovery and development. Many of the metabolites belong to different classes i.e. alkaloids, benzopyranones, coumarins, chromones, cytochalasines, enniatines, isocoumarin derivatives, quinones, peptides, phenols, phenolic acids, semiquinones, steroids, terpenoids, xanthones and lactones. One of the most widely studied endophytic genera is Pestalotiopsis, from which more than 140 metabolites are reported with antimicrobial, antioxidant and antitumor activities. Besides reviewing the advances made in identifying bioactive metabolites with drug development potential from endophytic fungi, this chapter discusses possibilities and bottlenecks involved in employment of endophytic fungi and their products by the pharmaceutical industry. Furthermore, issues involved in anti-infective discovery and timeline of drug development are discussed in the view of developing new drug compounds from endophytic products.
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Affiliation(s)
- Anna Maria Pirttilä
- , Department of Biology, University of Oulu, Linnanmaa Biologintie A6, Oulu, 90570 Finland
| | - A. Carolin Frank
- , School of Natural Sciences, University of California, Merced, North Lake Road 5200, Merced, 95343 California USA
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Chen F, Lin L, Wang L, Tan Y, Zhou H, Wang Y, Wang Y, He W. Distribution of dTDP-glucose-4,6-dehydratase gene and diversity of potential glycosylated natural products in marine sediment-derived bacteria. Appl Microbiol Biotechnol 2011; 90:1347-59. [PMID: 21336933 DOI: 10.1007/s00253-011-3112-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 01/01/2011] [Accepted: 01/10/2011] [Indexed: 11/28/2022]
Abstract
To investigate the distribution of dTDP-glucose-4,6-dehydratase (dTGD) gene and diversity of the potential 6-deoxyhexose (6DOH) glycosylated compounds in marine microorganisms, a total of 91 marine sediment-derived bacteria, representing 48 operational taxonomic units and belonging to 25 genera, were screened by polymerase chain reaction. In total, 84% of the strains were dTGD gene positive, suggesting 6DOH biosynthetic pathway is widespread in these marine sediment-derived bacteria. BLASTp results of dTGD gene fragments indicate a high chemical diversity of the potential 6DOH glycosylated compounds. Close phylogenetic relationship occurred between dTGDs involved in the production of same or similar 6DOH glycosylated compounds, suggesting dTGD can be used to predict the structure of potential 6DOH glycosylated compounds produced by new strains. In two cases, where dTGD shared ≥85% amino acid identity and close phylogenetic relationship with their counterparts, 6DOH glycosylated compounds were accurately predicted. Our results demonstrate that phylogenetic analysis of dTGD gene is useful for structure prediction of glycosylated compounds from newly isolated strains and can therefore guide the chemical purification and structure identification process. The rapid identification of strains that possess dTGD gene provides a bioinformatics assessment of the greatest potential to produce glycosylated compounds despite the absence of fully biosynthetic pathways or genome sequences.
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Affiliation(s)
- Feifei Chen
- Key Laboratory of Biotechnology of Antibiotics, Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
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Bedekar A, Shah K, Koffas M. Natural Products for Type II Diabetes Treatment. ADVANCES IN APPLIED MICROBIOLOGY 2010; 71:21-73. [DOI: 10.1016/s0065-2164(10)71002-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Ryan KS, Drennan CL. Divergent pathways in the biosynthesis of bisindole natural products. ACTA ACUST UNITED AC 2009; 16:351-64. [PMID: 19389622 DOI: 10.1016/j.chembiol.2009.01.017] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 01/19/2009] [Accepted: 01/22/2009] [Indexed: 12/25/2022]
Abstract
Two molecules of the amino acid L-tryptophan are the biosynthetic precursors to a class of natural products named the "bisindoles." Hundreds of these bisindole molecules have been isolated from natural sources, and many of these molecules have potent medicinal properties. Recent studies have clarified the biosynthetic construction of six bisindole molecules, revealing novel enzymatic mechanisms and leading to combinatorial synthesis of new bisindole compounds. Collectively, these results provide a vantage point for understanding how much of the diversity of the bisindole class is generated from a small number of diverging pathways from L-tryptophan, as well as enabling identification of bisindoles that are likely derived via completely distinct biosynthetic pathways.
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Affiliation(s)
- Katherine S Ryan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Ramos A, Lombó F, Braña AF, Rohr J, Méndez C, Salas JA. Biosynthesis of elloramycin in Streptomyces olivaceus requires glycosylation by enzymes encoded outside the aglycon cluster. MICROBIOLOGY-SGM 2008; 154:781-788. [PMID: 18310024 DOI: 10.1099/mic.0.2007/014035-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Elloramycin is an anthracycline-like antitumour drug produced by Streptomyces olivaceus Tü2353. Cosmid cos16F4 has been previously shown to direct the biosynthesis of the elloramycin aglycon 8-demethyltetracenomycin C (8-DMTC), but not elloramycin. Sequencing of the 24.2 kb insert in cos16F4 shows the presence of 17 genes involved in elloramycin biosynthesis (elm genes) together with another additional eight ORFs probably not involved in elloramycin biosynthesis. The 17 genes would code for the biosynthesis of the polyketide moiety, sugar transfer, methylation of the tetracyclic ring and the sugar moiety, and export. Four genes (rhaA, rhaB, rhaC and rhaD) encoding the enzymic activities required for the biosynthesis of the sugar l-rhamnose were also identified in the S. olivaceus chromosome. The involvement of this rhamnose gene cluster in elloramycin biosynthesis was demonstrated by insertional inactivation of the rhaB gene, generating a non-producer mutant that accumulates the 8-DMTC C aglycon. Coexpression of cos16F4 with pEM4RO (expressing the four rhamnose biosynthesis genes) in Streptomyces lividans led to the formation of elloramycin, demonstrating that both subclusters are required for elloramycin biosynthesis. These results demonstrate that, in contrast to most of the biosynthesis gene clusters from actinomycetes, genes involved in the biosynthesis of elloramycin are located in two chromosomal loci.
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Affiliation(s)
- Angelina Ramos
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - Felipe Lombó
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - Alfredo F Braña
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - Jürgen Rohr
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536-0082, USA
| | - Carmen Méndez
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - José A Salas
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
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Cong L, Piepersberg W. Cloning and characterization of genes encoded in dTDP-D-mycaminose biosynthetic pathway from a midecamycin-producing strain, Streptomyces mycarofaciens. Acta Biochim Biophys Sin (Shanghai) 2007; 39:187-93. [PMID: 17342257 DOI: 10.1111/j.1745-7270.2007.00265.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Two subclusters from Streptomyces mycarofaciens, a midecamycin producer, were cloned and partially sequenced. One region was located at the 5' end of the mid polyketide synthase (PKS) genes and contained the genes midA, midB and midC. The other region was at the 3' end of the PKS genes and contained midK, midI and midH. Analysis of the nucleotide sequence revealed that these genes encode dTDP-glucose synthase (midA), dTDP-glucose dehydratase (midB), aminotransferase (midC), methyltransferase (midK), glycosyltransferase (midI) and an assistant gene (midH). All of these genes are involved in the biosynthesis of dTDP-D-mycaminose, the first deoxysugar of midecamycin, and in transferring the mycaminose to the midecamycin aglycone in S. mycarofaciens. Similar to gene pairs desVIII/desVII in S. venezuelae and tylMIII/tylMII in S. fradiae, the product of midH probably functions as an auxiliary protein required by the MidI protein for efficient glycosyltransfer in midecamycin biosynthesis.
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Affiliation(s)
- Lina Cong
- College of Biology and Food Technology, Dalian Institute of Light Industry, Dalian, China.
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Lamichhane J, Liou K, Lee HC, Kim CG, Sohng JK. Functional characterization of ketoreductase (rubN6) and aminotransferase (rubN4) genes in the gene cluster of Streptomyces achromogenes var. rubradiris. Biotechnol Lett 2006; 28:545-53. [PMID: 16614891 DOI: 10.1007/s10529-006-0013-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 01/16/2006] [Indexed: 10/24/2022]
Abstract
ORF's for rubN6 and rubN4 have been annotated as thymidine diphosphate glucose 4-ketoreductase and thymidine diphosphate glucose 3-aminotransferase by sequence analysis of the rubradirin biosynthetic gene cluster cloned from Streptomyces achromogenes var. rubradiris NRRL 3061. Both ORFs were heterologously expressed in Escherichia coli as His-tagged fusion proteins. The functionalities of TDP-glucose 4-ketoreductase and TDP-glucose 3-aminotransferase were verified by in vitro enzyme assay, and a biosynthetic pathway for TDP-D: -rubranitrose is proposed.
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Affiliation(s)
- Janardan Lamichhane
- Department of Pharmaceutical Engineering, Institute of Biomolecule Reconstruction, IBR, SunMoon University, Tangjeonmyun, 336-708, Asan-si, Chung-nam, Republic of Korea
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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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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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Elling L, Rupprath C, Günther N, Römer U, Verseck S, Weingarten P, Dräger G, Kirschning A, Piepersberg W. An enzyme module system for the synthesis of dTDP-activated deoxysugars from dTMP and sucrose. Chembiochem 2005; 6:1423-30. [PMID: 15977277 DOI: 10.1002/cbic.200500037] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A flexible enzyme module system is presented that allows preparative access to important dTDP-activated deoxyhexoses from dTMP and sucrose. The strategic combination of the recombinant enzymes dTMP-kinase and sucrose synthase (SuSy), and the enzymes RmlB (4,6-dehydratase), RmlC (3,5-epimerase) and RmlD (4-ketoreductase) from the biosynthetic pathway of dTDP-beta-L-rhamnose was optimized. The SuSy module (dTMP-kinase, SuSy, +/-RmlB) yielded the precursor dTDP-alpha-D-glucose (2) or the biosynthetic intermediate dTDP-6-deoxy-4-keto-alpha-D-glucose (3) on a 0.2-0.6 g scale with overall yields of 62 % and 72 %, respectively. A two-step strategy in which the SuSy module was followed by the deoxysugar module (RmlC and RmlD) resulted in the synthesis of dTDP-beta-L-rhamnose (4; 24.1 micromol, overall yield: 35.9 %). Substitution of RmlC by DnmU from the dTDP-beta-L-daunosamine pathway of Streptomyces peucetius in this module demonstrated that DnmU acts in vitro as a 3,5-epimerase with 3 as substrate to yield 4 (32.2 mumol, overall yield: 44.7 %). Chemical reduction of 3 with NaBH4 gave a mixture of the C-4 epimers dTDP-alpha-D-quinovose (6) and dTDP-alpha-D-fucose (7) in a ratio of 2:1. In summary, the modular character of the presented enzyme system provides valuable compounds for the biochemical characterization of deoxysugar pathways playing a major role in microbial producers of antibiotic and antitumour agents.
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Affiliation(s)
- Lothar Elling
- Department of Biotechnology/Biomaterial Sciences and Helmholtz Institute for Biomedical Engineering, RWTH Aachen, Worringerweg 1, 52056 Aachen, Germany.
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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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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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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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Räty K, Hautala A, Torkkell S, Kantola J, Mäntsälä P, Hakala J, Ylihonko K. Characterization of mutations in aclacinomycin A-non-producing Streptomyces galilaeus strains with altered glycosylation patterns. MICROBIOLOGY (READING, ENGLAND) 2002; 148:3375-3384. [PMID: 12427929 DOI: 10.1099/00221287-148-11-3375] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study a set of Streptomyces galilaeus ATCC 31615 mutants was characterized, which are incapable of synthesizing some or all of the deoxyhexose sugars of aclacinomycin A. Complementation experiments with the the mutant strains H026, H038, H039, H054, H063, H065 and H075 were carried out with glycosylation genes previously derived from the wild-type S. galilaeus. Mutations in strains H038, H063 and H075 were complemented with single PCR-amplified genes. Furthermore, amplification and sequencing of the corresponding genes from the mutant strains revealed single point mutations in the sequences. First, in H038 a transition mutation in aknQ, encoding a putative dTDP-hexose 3-ketoreductase, causes an amino acid substitution from glycine to aspartate, suppressing the biosynthesis of both 2-deoxyfucose and rhodinose and thus leading to the accumulation of aclacinomycin T with rhodosamine as its only sugar. Second, in H063, which accumulates aklavinone without a sugar moiety, amino acid substitution occurs, with threonine being substituted by isoleucine in dTDP-glucose synthase, the first enzyme participating in deoxyhexose biosynthesis, encoded by aknY. Third, a nonsense mutation in aknP leads to truncated dTDP-hexose 3-dehydratase in H075, which is incapable of synthesizing rhodinose. In addition, mutants H054 and H065, which accumulate aclacinomycins without aminosugars, were complemented by a gene for an aminotransferase, aknZ. Characterization of the nature of the mutations adds to the usefulness and value of the mutants in the analysis of gene function and in the creation of novel compounds by combinatorial biosynthesis. Furthermore, these results strengthen the assignments of akn gene products and enlighten the biosynthetic pathway for deoxyhexoses.
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Affiliation(s)
- Kaj Räty
- Department of Biochemistry and Food Chemistry, University of Turku, Vatselankatu 2,FIN-20014, Turku, Finland1
| | - Anne Hautala
- Galilaeus Oy, PO Box 113, FIN-20781, Kaarina, Finland2
| | - Sirke Torkkell
- Department of Biochemistry and Food Chemistry, University of Turku, Vatselankatu 2,FIN-20014, Turku, Finland1
| | - Jaana Kantola
- Galilaeus Oy, PO Box 113, FIN-20781, Kaarina, Finland2
| | - Pekka Mäntsälä
- Department of Biochemistry and Food Chemistry, University of Turku, Vatselankatu 2,FIN-20014, Turku, Finland1
| | - Juha Hakala
- Galilaeus Oy, PO Box 113, FIN-20781, Kaarina, Finland2
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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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Shima S, Warkentin E, Thauer RK, Ermler U. Structure and function of enzymes involved in the methanogenic pathway utilizing carbon dioxide and molecular hydrogen. J Biosci Bioeng 2002; 93:519-30. [PMID: 16233244 DOI: 10.1016/s1389-1723(02)80232-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2002] [Accepted: 05/07/2002] [Indexed: 11/29/2022]
Abstract
Methane is an end product of anaerobic degradation of organic compounds in fresh water environments such as lake sediments and the intestinal tract of animals. Methanogenic archaea produce methane from carbon dioxide and molecular hydrogen, acetate and C1 compounds such as methanol in an energy gaining process. The methanogenic pathway utilizing carbon dioxide and molecular hydrogen involves ten methanogen specific enzymes, which catalyze unique reactions using novel coenzymes. These enzymes have been purified and biochemically characterized. The genes encoding the enzymes have been cloned and sequenced. Recently, crystal structures of five methanogenic enzymes: formylmethanofuran : tetrahydromethanopterin formyltransferase, methenyltetrahydromethanopterin cyclohydrolase, methylenetetrahydromethanopterin reductase, F420H2:NADP oxidoreductase and methyl-coenzyme M reductase were reported. In this review, we describe the pathway utilizing carbon dioxide and molecular hydrogen and the catalytic mechanisms of the enzymes based on their crystal structures.
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Affiliation(s)
- Seigo Shima
- Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Karl-von-Frisch Strasse, D-35043 Marburg, Germany.
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19
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Trefzer A, Fischer C, Stockert S, Westrich L, Künzel E, Girreser U, Rohr J, Bechthold A. Elucidation of the function of two glycosyltransferase genes (lanGT1 and lanGT4) involved in landomycin biosynthesis and generation of new oligosaccharide antibiotics. CHEMISTRY & BIOLOGY 2001; 8:1239-52. [PMID: 11755402 DOI: 10.1016/s1074-5521(01)00091-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND The genetic engineering of antibiotic-producing Streptomyces strains is an approach that became a successful methodology in developing new natural polyketide derivatives. Glycosyltransferases are important biosynthetic enzymes that link sugar moieties to aglycones, which often derive from polyketides. Biological activity is frequently generated along with this process. Here we report the use of glycosyltransferase genes isolated from the landomycin biosynthetic gene cluster to create hybrid landomycin/urdamycin oligosaccharide antibiotics. RESULTS Production of several novel urdamycin derivatives by a mutant of Streptomyces fradiae Tü2717 has been achieved in a combinatorial biosynthetic approach using glycosyltransferase genes from the landomycin producer Streptomyces cyanogenus S136. For the generation of gene cassettes useful for combinatorial biosynthesis experiments new vectors named pMUNI, pMUNII and pMUNIII were constructed. These vectors facilitate the construction of gene combinations taking advantage of the compatible MunI and EcoRI restriction sites. CONCLUSIONS The high-yielding production of novel oligosaccharide antibiotics using glycosyltransferase gene cassettes generated in a very convenient way proves that glycosyltransferases can be flexible towards the alcohol substrate. In addition, our results indicate that LanGT1 from S. cyanogenus S136 is a D-olivosyltransferase, whereas LanGT4 is a L-rhodinosyltransferase.
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Affiliation(s)
- A Trefzer
- Albert-Ludwigs-Universität Freiburg im Breisgau, Pharmazeutische Biologie, Freiburg, Germany
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20
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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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21
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Albermann C, Piepersberg W. Expression and identification of the RfbE protein from Vibrio cholerae O1 and its use for the enzymatic synthesis of GDP-D-perosamine. Glycobiology 2001; 11:655-61. [PMID: 11479276 DOI: 10.1093/glycob/11.8.655] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The 4-amino-6-deoxy-monosaccharide D-perosamine is an important element in the glycosylation of interesting cell products, such as antibiotics and lipopolysaccharides (LPS) of Gram-positive and Gram-negative bacteria. The biosynthetic pathway of the precursor molecule, GDP-D-perosamine, in Vibrio cholerae O1 starts with an isomerisation of fructose-6-phosphate catalyzed by the bifunctional enzyme phosphomannose isomerase-guanosine diphosphomannose pyrophosphorylase (RfbA; E.C. 2.7.7.22) creating the intermediate mannose-6-phosphate, which is subsequently converted by the phosphomanno-mutase (RfbB; E.C. 5.4.2.8) and further by RfbA to GDP-D-mannose, to GDP-4 keto-6-deoxymannose by a 4,6-dehydratase (RfbD; E.C. 4.2.1.47) and finally to GDP-D-perosamine by an aminotransferase (RfbE; E.C. not yet classified). We cloned the rfbD and the rfbE genes of V. cholerae O1 in Escherichia coli expression vectors. Both biosynthetic enzymes were overproduced in E. coli BL21 (DE3) and their activities were analyzed. The enzymatic conversion from GDP-D-mannose to GDP-D-perosamine was optimized and the final product, GDP-D-perosamine, was purified and identified by nuclear magnetic resonance, mass spectrometry, and chromatography. The catalytically active form of the GDP-4-keto-6-deoxy-D-mannose-4-aminotransferase seems to be a tetramer of 170 kDa. The His-tag RfbE fusion protein has a Km of 0.06 mM and a Vmax value of 38 nkat/mg protein for the substrate GDP-4-keto-6-deoxy-D-mannose. The Km and Vmax values for the cosubstrate L-glutamate were 0.1 mM and 42 nkat/mg protein, respectively. The intention of this work is to establish a basis for both the in vitro production of GDP-D-perosamine and for an in vivo perosaminylation system in a suitable bacterial host, preferably E. coli.
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Affiliation(s)
- C Albermann
- Chemische Mikrobiologie, Bergische Universität GH Wuppertal, Gauss-Str. 20, D-42097, Germany
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22
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Patallo EP, Blanco G, Fischer C, Brana AF, Rohr J, Mendez C, Salas JA. Deoxysugar Methylation during Biosynthesis of the Antitumor Polyketide Elloramycin by Streptomyces olivaceus. J Biol Chem 2001; 276:18765-74. [PMID: 11376004 DOI: 10.1074/jbc.m101225200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The anthracycline-like polyketide drug elloramycin is produced by Streptomyces olivaceus Tü2353. Elloramycin has antibacterial activity against Gram-positive bacteria and also exhibits antitumor activity. From a cosmid clone (cos16F4) containing part of the elloramycin biosynthesis gene cluster, three genes (elmMI, elmMII, and elmMIII) have been cloned. Sequence analysis and data base comparison showed that their deduced products resembled S-adenosylmethionine-dependent O-methyltransferases. The genes were individually expressed in Streptomyces albus and also coexpressed with genes involved in the biosynthesis of l-rhamnose, the 6-deoxysugar attached to the elloramycin aglycon. The resulting recombinant strains were used to biotransform three different elloramycin-type compounds: l-rhamnosyl-tetracenomycin C, l-olivosyl-tetracenomycin C, and l-oleandrosyl-tetracenomycin, which differ in their 2'-, 3'-, and 4'-substituents of the sugar moieties. When only the three methyltransferase-encoding genes elmMI, elmMII, and elmMIII were individually expressed in S. albus, the methylating activity of the three methyltransferases was also assayed in vitro using various externally added glycosylated substrates. From the combined results of all of these experiments, it is proposed that methyltransferases ElmMI, ElmMII, and ElmMIII are involved in the biosynthesis of the permethylated l-rhamnose moiety of elloramycin. ElmMI, ElmMII, and ElmMIII are responsible for the consecutive methylation of the hydroxy groups at the 2'-, 3'-, and 4'-position, respectively, after the sugar moiety has been attached to the aglycon.
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Affiliation(s)
- E P Patallo
- Departamento de Biologia Funcional e Instituto Universitario de Oncologia del Principado de Asturias, Universidad de Oviedo, 33006 Oviedo, Spain
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23
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Blanco G, Patallo EP, Braña AF, Trefzer A, Bechthold A, Rohr J, Méndez C, Salas JA. Identification of a sugar flexible glycosyltransferase from Streptomyces olivaceus, the producer of the antitumor polyketide elloramycin. CHEMISTRY & BIOLOGY 2001; 8:253-63. [PMID: 11306350 DOI: 10.1016/s1074-5521(01)00010-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Elloramycin is an anthracycline-like antitumor drug related to tetracenomycin C which is produced by Streptomyces olivaceus Tü2353. Structurally is a tetracyclic aromatic polyketide derived from the condensation of 10 acetate units. Its chromophoric aglycon is glycosylated with a permethylated L-rhamnose moiety at the C-8 hydroxy group. Only limited information is available about the genes involved in the biosynthesis of elloramycin. From a library of chromosomal DNA from S. olivaceus, a cosmid (16F4) was isolated that contains part of the elloramycin gene cluster and when expressed in Streptomyces lividans resulted in the production of a non-glycosylated intermediate in elloramycin biosynthesis, 8-demethyl-tetracenomycin C (8-DMTC). RESULTS The expression of cosmid 16F4 in several producers of glycosylated antibiotics has been shown to produce tetracenomycin derivatives containing different 6-deoxysugars. Different experimental approaches showed that the glycosyltransferase gene involved in these glycosylation events was located in 16F4. Using degenerated oligoprimers derived from conserved amino acid sequences in glycosyltransferases, the gene encoding this sugar flexible glycosyltransferase (elmGT) has been identified. After expression of elmGT in Streptomyces albus under the control of the erythromycin resistance promoter, ermEp, it was shown that elmG can transfer different monosaccharides (both L- and D-sugars) and a disaccharide to 8-DMTC. Formation of a diolivosyl derivative in the mithramycin producer Streptomyces argillaceus was found to require the cooperative action of two mithramycin glycosyltransferases (MtmGI and MtmGII) responsible for the formation of the diolivosyl disaccharide, which is then transferred by ElmGT to 8-DMTC. CONCLUSIONS The ElmGT glycosyltransferase from S. olivaceus Tü2353 can transfer different sugars into the aglycon 8-DMTC. In addition to its natural sugar substrate L-rhamnose, ElmGT can transfer several L- and D-sugars and also a diolivosyl disaccharide into the aglycon 8-DMTC. ElmGT is an example of sugar flexible glycosyltransferase and can represent an important tool for combinatorial biosynthesis.
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Affiliation(s)
- G Blanco
- Departamento of Biología, Functional e Instituto Universitario del Principado de Asturias, Universidad de Oviedo, Spain
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Albermann C, Distler J, Piepersberg W. Preparative synthesis of GDP-beta-L-fucose by recombinant enzymes from enterobacterial sources. Glycobiology 2000; 10:875-81. [PMID: 10988249 DOI: 10.1093/glycob/10.9.875] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 6-deoxyhexose L-fucose is an important and characteristic element in glycoconjugates of bacteria (e.g., lipopolysaccharides), plants (e.g., xyloglucans) and animals (e.g., glycolipids, glycoproteins, and oligosaccharides). The biosynthetic pathway of GDP-L-fucose starts with a dehydration of GDP-D-mannose catalyzed by GDP-D-mannose 4,6-dehydratase (Gmd) creating GDP-4-keto-6-deoxymannose which is subsequently converted by the GDP-4-keto-6-deoxy-D-mannose 3,5-epimerase-4-reductase (WcaG; GDP-beta-L-fucose synthetase) to GDP-beta-L-fucose. Both biosynthetic genes gmd and wcaG were cloned from Escherichia coli K12 and the enzymes overexpressed under control of the T7 promoter in the expression vectors pET11a and pET16b, yielding both native and N-terminal His-tag fusion proteins, respectively. The activities of the Gmd and WcaG were analyzed. The enzymatic conversion from GDP-D-mannose to GDP-beta-L-fucose was optimized and the final product was purified. The formation of GDP-beta-L-fucose by the recombinant enzymes was verified by HPLC and NMR analyses. The His-tag fusion variants of the Gmd and WcaG proteins were purified to near homogeneity. The His-tag Gmd recombinant enzyme was inactive, whereas His-tag WcaG showed very similar enzymatic properties relative to the native GDP-beta-L-fucose synthetase. With the purified His-tag WcaG Km and Vmax values, respectively, of 40 microM and 23 nkat/mg protein for the substrate GDP-4-keto-6-deoxy-D-mannose and of 21 microM and 10 nkat/mg protein for the cosubstrate NADPH were obtained; a pH optimum of 7.5 was determined and the enzyme was stimulated to equal extend by the divalent cations Mg2+ and Ca2+. The Gmd enzyme showed a strong feedback inhibition by GDP-beta-L-fucose.
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Affiliation(s)
- C Albermann
- Chemische Mikrobiologie, Bergische Universität Wuppertal, Germany
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25
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Steffensky M, Mühlenweg A, Wang ZX, Li SM, Heide L. Identification of the novobiocin biosynthetic gene cluster of Streptomyces spheroides NCIB 11891. Antimicrob Agents Chemother 2000; 44:1214-22. [PMID: 10770754 PMCID: PMC89847 DOI: 10.1128/aac.44.5.1214-1222.2000] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/1999] [Accepted: 01/29/2000] [Indexed: 11/20/2022] Open
Abstract
The novobiocin biosynthetic gene cluster from Streptomyces spheroides NCIB 11891 was cloned by using homologous deoxynucleoside diphosphate (dNDP)-glucose 4,6-dehydratase gene fragments as probes. Double-stranded sequencing of 25.6 kb revealed the presence of 23 putative open reading frames (ORFs), including the gene for novobiocin resistance, gyrB(r), and at least 11 further ORFs to which a possible role in novobiocin biosynthesis could be assigned. An insertional inactivation experiment with a dNDP-glucose 4, 6-dehydratase fragment resulted in abolishment of novobiocin production, since biosynthesis of the deoxysugar moiety of novobiocin was blocked. Heterologous expression of a key enzyme of novobiocin biosynthesis, i.e., novobiocic acid synthetase, in Streptomyces lividans TK24 further confirmed the involvement of the analyzed genes in the biosynthesis of the antibiotic.
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Affiliation(s)
- M Steffensky
- Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, 72076 Tübingen, Germany
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26
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Aguirrezabalaga I, Olano C, Allende N, Rodriguez L, Braña AF, Méndez C, Salas JA. Identification and expression of genes involved in biosynthesis of L-oleandrose and its intermediate L-olivose in the oleandomycin producer Streptomyces antibioticus. Antimicrob Agents Chemother 2000; 44:1266-75. [PMID: 10770761 PMCID: PMC89854 DOI: 10.1128/aac.44.5.1266-1275.2000] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 9.8-kb DNA region from the oleandomycin gene cluster in Streptomyces antibioticus was cloned. Sequence analysis revealed the presence of 8 open reading frames encoding different enzyme activities involved in the biosynthesis of one of the two 2, 6-deoxysugars attached to the oleandomycin aglycone: L-oleandrose (the oleW, oleV, oleL, and oleU genes) and D-desosamine (the oleNI and oleT genes), or of both (the oleS and oleE genes). A Streptomyces albus strain harboring the oleG2 glycosyltransferase gene integrated into the chromosome was constructed. This strain was transformed with two different plasmid constructs (pOLV and pOLE) containing a set of genes proposed to be required for the biosynthesis of dTDP-L-olivose and dTDP-L-oleandrose, respectively. Incubation of these recombinant strains with the erythromycin aglycon (erythronolide B) gave rise to two new glycosylated compounds, identified as L-3-O-olivosyl- and L-3-O-oleandrosyl-erythronolide B, indicating that pOLV and pOLE encode all enzyme activities required for the biosynthesis of these two 2,6-dideoxysugars. A pathway is proposed for the biosynthesis of these two deoxysugars in S. antibioticus.
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Affiliation(s)
- I Aguirrezabalaga
- Departamento de Biología Funcional e Instituto Universitario de Oncología de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
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27
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28
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Abstract
There is currently intense interest in unravelling the modus operandi of type I modular polyketide synthases in order to lay the ground work for their use in the combinatorial biosynthesis of new bioactive molecules. Much of our knowledge is derived from studies on 6-deoxyerythronolide B (DEBS), the enzyme assembling the polyketide backbone of erythromycin. Work on the rifamycin polyketide synthase has revealed a number of features that differ from those seen with DEBS.
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Affiliation(s)
- H G Floss
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA.
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29
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Stratmann A, Mahmud T, Lee S, Distler J, Floss HG, Piepersberg W. The AcbC protein from Actinoplanes species is a C7-cyclitol synthase related to 3-dehydroquinate synthases and is involved in the biosynthesis of the alpha-glucosidase inhibitor acarbose. J Biol Chem 1999; 274:10889-96. [PMID: 10196166 DOI: 10.1074/jbc.274.16.10889] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The putative biosynthetic gene cluster for the alpha-glucosidase inhibitor acarbose was identified in the producer Actinoplanes sp. 50/110 by cloning a DNA segment containing the conserved gene for dTDP-D-glucose 4,6-dehydratase, acbB. The two flanking genes were acbA (dTDP-D-glucose synthase) and acbC, encoding a protein with significant similarity to 3-dehydroquinate synthases (AroB proteins). The acbC gene was overexpressed heterologously in Streptomyces lividans 66, and the product was shown to be a C7-cyclitol synthase using sedo-heptulose 7-phosphate, but not ido-heptulose 7-phosphate, as its substrate. The cyclization product, 2-epi-5-epi-valiolone ((2S,3S,4S,5R)-5-(hydroxymethyl)cyclohexanon-2,3,4,5-tetrol), is a precursor of the valienamine moiety of acarbose. A possible five-step reaction mechanism is proposed for the cyclization reaction catalyzed by AcbC based on the recent analysis of the three-dimensional structure of a eukaryotic 3-dehydroquinate synthase domain (Carpenter, E. P., Hawkins, A. R., Frost, J. W., and Brown, K. A. (1998) Nature 394, 299-302).
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Affiliation(s)
- A Stratmann
- Chemische Mikrobiologie, FB9-Chemie, Bergische Universität GH Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany
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30
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Mao Y, Varoglu M, Sherman DH. Genetic localization and molecular characterization of two key genes (mitAB) required for biosynthesis of the antitumor antibiotic mitomycin C. J Bacteriol 1999; 181:2199-208. [PMID: 10094699 PMCID: PMC93634 DOI: 10.1128/jb.181.7.2199-2208.1999] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/1998] [Accepted: 01/12/1999] [Indexed: 11/20/2022] Open
Abstract
Mitomycin C (MC) is an antitumor antibiotic derived biosynthetically from 3-amino-5-hydroxybenzoic acid (AHBA), D-glucosamine, and carbamoyl phosphate. A gene (mitA) involved in synthesis of AHBA has been identified and found to be linked to the MC resistance locus, mrd, in Streptomyces lavendulae. Nucleotide sequence analysis showed that mitA encodes a 388-amino-acid protein that has 71% identity (80% similarity) with the rifamycin AHBA synthase from Amycolatopsis mediterranei, as well as with two additional AHBA synthases from related ansamycin antibiotic-producing microorganisms. Gene disruption and site-directed mutagenesis of the S. lavendulae chromosomal copy of mitA completely blocked the production of MC. The function of mitA was confirmed by complementation of an S. lavendulae strain containing a K191A mutation in MitA with AHBA. A second gene (mitB) encoding a 272-amino-acid protein (related to a group of glycosyltransferases) was identified immediately downstream of mitA that upon disruption resulted in abrogation of MC synthesis. This work has localized a cluster of key genes that mediate assembly of the unique mitosane class of natural products.
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Affiliation(s)
- Y Mao
- Department of Microbiology and Biological Process Technology Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
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31
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Westrich L, Domann S, Faust B, Bedford D, Hopwood DA, Bechthold A. Cloning and characterization of a gene cluster from Streptomyces cyanogenus S136 probably involved in landomycin biosynthesis. FEMS Microbiol Lett 1999; 170:381-7. [PMID: 9933932 DOI: 10.1111/j.1574-6968.1999.tb13398.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
From a cosmid library of Streptomyces cyanogenus S136, DNA fragments encompassing approximately 35 kb of the presumed landomycin biosynthetic gene cluster were identified and sequenced, revealing 32 open reading frames most of which could be assigned through data base comparison.
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Affiliation(s)
- L Westrich
- Institut für Pharmazeutische Biologie, Universität Tübingen, Germany
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32
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Salas JA, Méndez C. Genetic manipulation of antitumor-agent biosynthesis to produce novel drugs. Trends Biotechnol 1998; 16:475-82. [PMID: 9830156 DOI: 10.1016/s0167-7799(98)01198-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Current methods of obtaining novel drugs may be complemented in the near future by the genetic engineering of antitumor-agent biosynthesis in microorganisms. Biosynthetic gene clusters from several antitumor pathways in actinomycetes are presently being characterized and expressed in order to generate novel drugs. Several novel hydroxylated and glycosylated antitumor-drug derivatives have been produced that show a relaxed substrate specificity for secondary-metabolic enzymes, which opens up the possibility of generating novel drugs by genetic manipulation.
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Affiliation(s)
- J A Salas
- Departamento de Biologia Funcional e Instituto Universitario de Biotecnologia de Asturias (IUBA-CSIC), Universidad de Oviedo, Spain.
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33
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Fernández E, Weissbach U, Sánchez Reillo C, Braña AF, Méndez C, Rohr J, Salas JA. Identification of two genes from Streptomyces argillaceus encoding glycosyltransferases involved in transfer of a disaccharide during biosynthesis of the antitumor drug mithramycin. J Bacteriol 1998; 180:4929-37. [PMID: 9733697 PMCID: PMC107519 DOI: 10.1128/jb.180.18.4929-4937.1998] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mithramycin is an antitumor polyketide drug produced by Streptomyces argillaceus that contains two deoxysugar chains, a disaccharide consisting of two D-olivoses and a trisaccharide consisting of a D-olivose, a D-oliose, and a D-mycarose. From a cosmid clone (cosAR3) which confers resistance to mithramycin in streptomycetes, a 3-kb PstI-XhoI fragment was sequenced, and two divergent genes (mtmGI and mtmGII) were identified. Comparison of the deduced products of both genes with proteins in databases showed similarities with glycosyltransferases and glucuronosyltransferases from different sources, including several glycosyltransferases involved in sugar transfer during antibiotic biosynthesis. Both genes were independently inactivated by gene replacement, and the mutants generated (M3G1 and M3G2) did not produce mithramycin. High-performance liquid chromatography analysis of ethyl acetate extracts of culture supernatants of both mutants showed the presence of several peaks with the characteristic spectra of mithramycin biosynthetic intermediates. Four compounds were isolated from both mutants by preparative high-performance liquid chromatography, and their structures were elucidated by physicochemical methods. The structures of these compounds were identical in both mutants, and the compounds are suggested to be glycosylated intermediates of mithramycin biosynthesis with different numbers of sugar moieties attached to C-12a-O of a tetracyclic mithramycin precursor and to C-2-O of mithramycinone: three tetracyclic intermediates containing one sugar (premithramycin A1), two sugars (premithramycin A2), or three sugars (premithramycin A3) and one tricyclic intermediate containing a trisaccharide chain (premithramycin A4). It is proposed that the glycosyltransferases encoded by mtmGI and mtmGII are responsible for forming and transferring the disaccharide during mithramycin biosynthesis. From the structures of the new metabolites, a new biosynthetic sequence regarding late steps of mithramycin biosynthesis can be suggested, a sequence which includes glycosyl transfer steps prior to the final shaping of the aglycone moiety of mithramycin.
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Affiliation(s)
- E Fernández
- Departamento de Biología Funcional e Instituto Universitario de Biotecnologia de Asturias, Universidad de Oviedo, 33006 Oviedo, Spain
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Kim CG, Yu TW, Fryhle CB, Handa S, Floss HG. 3-Amino-5-hydroxybenzoic acid synthase, the terminal enzyme in the formation of the precursor of mC7N units in rifamycin and related antibiotics. J Biol Chem 1998; 273:6030-40. [PMID: 9497318 DOI: 10.1074/jbc.273.11.6030] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biosynthesis of ansamycin antibiotics, like rifamycin B, involves formation of 3-amino-5-hydroxybenzoic acid (AHBA) by a novel variant of the shikimate pathway. AHBA then serves as the starter unit for the assembly of a polyketide which eventually links back to the amino group of AHBA to form the macrolactam ring. The terminal enzyme of AHBA formation, which catalyzes the aromatization of 5-deoxy-5-amino-3-dehydroshikimic acid, has been purified to homogeneity from Amycolatopsis mediterranei, the encoding gene has been cloned, sequenced, and overexpressed in Escherichia coli. The recombinant enzyme, a (His)6 fusion protein, as well as the native one, are dimers containing one molecule of pyridoxal phosphate per subunit. Mechanistic studies showed that the enzyme-bound pyridoxal phosphate forms a Schiff's base with the amino group of 5-deoxy-5-amino-3-dehydroshikimic acid and catalyzes both an alpha, beta-dehydration and a stereospecific 1,4-enolization of the substrate. Inactivation of the gene encoding AHBA synthase in the A. mediterranei genome results in loss of rifamycin formation; production of the antibiotic is restored when the mutant is supplemented with AHBA.
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Affiliation(s)
- C G Kim
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
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Gaisser S, Trefzer A, Stockert S, Kirschning A, Bechthold A. Cloning of an avilamycin biosynthetic gene cluster from Streptomyces viridochromogenes Tü57. J Bacteriol 1997; 179:6271-8. [PMID: 9335272 PMCID: PMC179539 DOI: 10.1128/jb.179.20.6271-6278.1997] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A 65-kb region of DNA from Streptomyces viridochromogenes Tü57, containing genes encoding proteins involved in the biosynthesis of avilamycins, was isolated. The DNA sequence of a 6.4-kb fragment from this region revealed four open reading frames (ORF1 to ORF4), three of which are fully contained within the sequenced fragment. The deduced amino acid sequence of AviM, encoded by ORF2, shows 37% identity to a 6-methylsalicylic acid synthase from Penicillium patulum. Cultures of S. lividans TK24 and S. coelicolor CH999 containing plasmids with ORF2 on a 5.5-kb PstI fragment were able to produce orsellinic acid, an unreduced version of 6-methylsalicylic acid. The amino acid sequence encoded by ORF3 (AviD) is 62% identical to that of StrD, a dTDP-glucose synthase from S. griseus. The deduced amino acid sequence of AviE, encoded by ORF4, shows 55% identity to a dTDP-glucose dehydratase (StrE) from S. griseus. Gene insertional inactivation experiments of aviE abolished avilamycin production, indicating the involvement of aviE in the biosynthesis of avilamycins.
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Affiliation(s)
- S Gaisser
- Pharmazeutisches Institut, Pharmazeutische Biologie, Universität Tübingen, Germany
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Piepersberg W. Molecular Biology, Biochemistry and Fermentation of Aminoglycoside Antibiotics. DRUGS AND THE PHARMACEUTICAL SCIENCES 1997. [DOI: 10.1201/b14856-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Lombó F, Siems K, Braña AF, Méndez C, Bindseil K, Salas JA. Cloning and insertional inactivation of Streptomyces argillaceus genes involved in the earliest steps of biosynthesis of the sugar moieties of the antitumor polyketide mithramycin. J Bacteriol 1997; 179:3354-7. [PMID: 9150235 PMCID: PMC179118 DOI: 10.1128/jb.179.10.3354-3357.1997] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Two genes (mtmD and mtmE) were cloned and sequenced from the mithramycin producer Streptomyces argillaceus. Comparison with proteins in databases and enzymatic assays after expression in Escherichia coli showed that they encode a glucose-1-phosphate:TTP thymidylyl transferase and a TDP-D-glucose 4,6-dehydratase, respectively. The mtmD gene was inactivated by gene replacement, generating a nonproducing mutant that accumulates a tetracyclic compound designated premithramycinone. The identification of premithramycinone reveals new aspects of the mithramycin biosynthetic pathway and suggests that at least some glycosylations occur before breakage of the fourth ring.
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Affiliation(s)
- F Lombó
- Departamento de Biología Funcional, Instituto Universitario de Biotecnología de Asturias (IUBA-CSIC), Universidad de Oviedo, Spain
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Kirschning A, Bechthold AFW, Rohr J. Chemical and biochemical aspects of deoxysugars and deoxysugar oligosaccharides. Top Curr Chem (Cham) 1997. [DOI: 10.1007/bfb0119234] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Elling L. Glycobiotechnology: enzymes for the synthesis of nucleotide sugars. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1997; 58:89-144. [PMID: 9103912 DOI: 10.1007/bfb0103303] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Complex carbohydrates, as constituting part of glycoconjugates such as glycoproteins, glycolipids, hormones, antibiotics and other secondary metabolites, play an active role in inter- and intracellular communication. The aim of "glycobiotechnology" as an upcoming interdisciplinary research field is to develop highly efficient synthesis strategies, including in vivo and in vitro approaches, in order to bring such complex molecules into analytical and therapeutic studies. The enzymatic synthesis of glycosidic bonds by Leloir-glycosyltransferases is an efficient strategy for obtaining saccharides with absolute stereo- and regioselectivity in high yields and under mild conditions. There are, however, two obstacles hindering the realization of this process on a biotechnological scale, namely the production of recombinant Leloir-glycosyltransferases and the availability of enzymes for the synthesis of nucleotide sugars (the glycosyltransferase donor substrates). The present review surveys some synthetic targets which have attracted the interest of glycobiologists as well as recombinant expression systems which give Leloir-glycosyltransferase activities in the mU and U range. The main part summarizes publications concerned with the complex pathways of primary and secondary nucleotide sugars and the availability and use of these enzymes for synthesis applications. In this context, a survey of our work will demonstrate how enzymes from different sources and pathways can be combined for the synthesis of nucleotide deoxysugars and oligosaccharides.
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Affiliation(s)
- L Elling
- Institut für Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf im Forschungszentrum Jülich, Germany
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Angucyclines: Total syntheses, new structures, and biosynthetic studies of an emerging new class of antibiotics. Top Curr Chem (Cham) 1997. [DOI: 10.1007/bfb0119236] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Klein AR, Berk H, Purwantini E, Daniels L, Thauer RK. Si-face stereospecificity at C5 of coenzyme F420 for F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 239:93-7. [PMID: 8706724 DOI: 10.1111/j.1432-1033.1996.0093u.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Coenzyme F420 is a 5-deazaflavin. Upon reduction, 1,5-dihydro-coenzyme F420 is formed with a prochiral center at C5. In this study we report that the F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and the F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus are Si-face stereospecific with respect to C5 of the 5-deazaflavin. These results were obtained by following the stereochemical course of the reversible incorporation of 3H into F420 from tritium-labeled substrates. Our findings bring to eight the number of coenzyme-F420-dependent enzymes shown to be Si-face stereospecific. No F420-dependent enzyme with Re-face stereospecificity is known. This is noteworthy since coenzyme F420 is functionally similar to pyridine nucleotides for which both Si-face and Re-face specific enzymes have been found.
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Affiliation(s)
- A R Klein
- Max-Planck-Institut für terrestrische Mikrobiologie, Philipps-Universität, Marburg, Germany
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Beyer S, Distler J, Piepersberg W. The str gene cluster for the biosynthesis of 5'-hydroxystreptomycin in Streptomyces glaucescens GLA.0 (ETH 22794): new operons and evidence for pathway-specific regulation by StrR. MOLECULAR & GENERAL GENETICS : MGG 1996; 250:775-84. [PMID: 8628239 DOI: 10.1007/bf02172990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Two divergently oriented operons, strXU and strVW, located within the gene cluster for 5'-hydroxystreptomycin (5'-OH-Sm) biosynthesis in Streptomyces glaucescens strain GAL.0 (ETH 22794), were analysed by DNA sequencing and transcription/regulation studies. Three genes, strU and strVW, are conserved in a similar arrangement but in a different location within the str/sts gene cluster of the Sm-producing strain S. griseus N2-3-11. The four putative products resemble NDP-4-ketohexose 3,5-epimerases (StrX, M(r) 20.2 kDa), NAD(P)-dependent oxidoreductases (StrU, 45.6 kDa), and ABC-transporters (StrV, 61.8 kDa; StrW, 63.4 kDa). These genes are apparently involved in the biosynthesis of 5'-OH-Sm because the promoters of both operons are activated in trans by the activator StrR of S. griseus N2-3-11, when cloned in S. lividans 66 TK23. A sequence motif resembling the consensus sequence GTTCGActG(N)11CagTcGAAc for binding of StrR was identified within the intergenic region of strX and strV. Specific binding of StrR to this site was demonstrated by gel retardation assays using purified His*Tag-StrR.
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Affiliation(s)
- S Beyer
- Bergische Universität GH Wuppertal, Germany
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Zervosen A, Stein A, Adrian H, Elling L. Combined enzymatic synthesis of nucleotide (deoxy) sugars from sucrose and nucleoside monophosphates. Tetrahedron 1996. [DOI: 10.1016/0040-4020(95)01081-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Tercero JA, Espinosa JC, Lacalle RA, Jiménez A. The biosynthetic pathway of the aminonucleoside antibiotic puromycin, as deduced from the molecular analysis of the pur cluster of Streptomyces alboniger. J Biol Chem 1996; 271:1579-90. [PMID: 8576156 DOI: 10.1074/jbc.271.3.1579] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The pur cluster which encodes the puromycin biosynthetic pathway from Streptomyces alboniger was subcloned as a 13-kilobase fragment in plasmid pIJ702 and expressed in an apparently regulated manner in the heterologous host Streptomyces lividans. The sequencing of a 9.1-kilobase DNA fragment completed the sequence of pur. This permitted identification of seven new open reading frames in the order: napH, pur7, pur10, pur6, pur4, pur5, and pur3. The latter is followed by the known pac, dmpM, and pur8 genes. Nine open reading frames are transcribed rightward as a unit in opposite direction to that of the pur8 gene which is expressed as a monocistronic transcript from the right-most end. napH encodes the known N-acetylpuromycin N-acetylhydrolase. The deduced products from other open reading frames present similarities to: NTP pyrophosphohydrolases (pur7), several oxidoreductases (pur10), the putative LmbC protein of the lincomycin biosynthetic pathway from Streptomyces lincolnensis (pur6), S-adenosylmethionine-dependent methyltransferases (pur5), a variety of presumed aminotransferases (pur4), and several monophosphatases (pur3). According to these similarities and to previous biochemical work, a puromycin biosynthetic pathway has been deduced. No cluster-associated regulatory gene was found. However, both pur10 and pur6 genes contain a TTA codon, which suggests that they are translationally controlled by the bldA gene product, a specific tRNA(Leu).
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Affiliation(s)
- J A Tercero
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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Vaupel M, Thauer RK. Coenzyme F420-dependent N5,N10-methylenetetrahydromethanopterin reductase (Mer) from Methanobacterium thermoautotrophicum strain Marburg. Cloning, sequencing, transcriptional analysis, and functional expression in Escherichia coli of the mer gene. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 231:773-8. [PMID: 7649177 DOI: 10.1111/j.1432-1033.1995.0773d.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The gene encoding the F420-dependent N5,N10-methylenetetrahydromethanopterin reductase (Mer), which catalyzes an intermediate step in methanogensis, was cloned and sequenced from the thermophilic Methanobacterium thermoautotrophicum strain Marburg. The gene was identified on a 3.8-kbp BamHI fragment of M. thermoautotrophicum genomic DNA using a homologous probe. The mer gene encoded an acidic protein of 321 amino acids, corresponding to a calculated molecular mass of 33,492 Da. Sequence analysis revealed the presence of a ribosome binding site, a putative promoter, and a possible terminator structure. The size of the mer mRNA was estimated as 1 kb indicating monocistronic transcription. The mer gene was expressed in Escherichia coli yielding an active enzyme of 36 kDa consistent with the apparent molecular mass described for the enzyme from M. thermoautotrophicum. Sequence comparisons revealed similarities between the F420-dependent N5,N10-methylenetetrahydromethanopterin reductase and a F420-dependent reductase involved in lincomycin biosynthesis in Streptomyces lincolnensis.
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Affiliation(s)
- M Vaupel
- Max-Planck-Institut für terrestrische Mikrobiologie, Philipps-Universität Marburg, Germany
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Vaupel M, Thauer RK. Coenzyme F420-Dependent N 5,N 10-Methylenetetrahydromethanopterin Reductase (Mer) from Methanobacterium Thermoautotrophicum Strain Marburg. Cloning, Sequencing, Transcriptional Analysis, and Functional Expression in Escherichia Coli of the mer Gene. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.tb20760.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Peschke U, Schmidt H, Zhang HZ, Piepersberg W. Molecular characterization of the lincomycin-production gene cluster of Streptomyces lincolnensis 78-11. Mol Microbiol 1995; 16:1137-56. [PMID: 8577249 DOI: 10.1111/j.1365-2958.1995.tb02338.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The lincomycin (LM)-production gene cluster of the overproducing strain Streptomyces lincolnensis 78-11 was cloned, analysed by hybridization, as well as by DNA sequencing, and compared with the respective genome segments of other lincomycin producers. The lmb/lmr gene cluster is composed of 27 open reading frames with putative biosynthetic or regulatory functions (lmb genes) and three resistance (lmr) genes, two of which, lmrA and lmrC, flank the cluster. A very similar overall organization of the lmb/lmr cluster seems to be conserved in four other LM producers, although the clusters are embedded in non-homologous genomic surroundings. In the wild-type strain (S. lincolnensis NRRL2936), the lmb/lmr-cluster apparently is present only in single copy. However, in the industrial strain S. lincolnensis 78-11 the non-adjacent gene clusters for the production of LM and melanin (melC) both are duplicated on a large (0.45-0.5 Mb) fragment, accompanied by deletion events. This indicates that enhanced gene dosage is one of the factors for the overproduction of LM and demonstrates that large-scale genome rearrangements can be a result of classical strain improvement by mutagenesis. Only a minority of the putative Lmb proteins belong to known protein families. These include members of the gamma-glutamyl transferases (LmbA), amino acid acylases (LmbC), aromatic amino acid aminotransferases (LmbF), imidazoleglycerolphosphate dehydratases (LmbK), dTDP-glucose synthases (LmbO), dTDP-glucose 4,6-dehydratases (LmbM) and (NDP-) ketohexose (or ketocyclitol) aminotransferases (LmbS). In contrast to earlier proposals on the biosynthetic pathway of the C-8 sugar moiety (methylthiolincosaminide), this branch of the LM pathway actually seems to be based on nucleotide-activated sugars as precursors.
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Affiliation(s)
- U Peschke
- Bergische Universität GH Wuppertal, Germany
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48
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Tsoi CJ, Khosla C. Combinatorial biosynthesis of 'unnatural' natural products: the polyketide example. CHEMISTRY & BIOLOGY 1995; 2:355-62. [PMID: 9383437 DOI: 10.1016/1074-5521(95)90214-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Multi-enzyme systems, such as those involved in the biosynthesis of polyketides, typically catalyze several distinct reactions that are combined in different ways to generate diverse natural products. The variability available in such systems has not been fully harnessed from nature. It may therefore be possible to create 'unnatural' natural products, which may be as structurally diverse and medicinally valuable as existing natural products, using combinatorial biosynthesis.
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Affiliation(s)
- C J Tsoi
- Department of Chemical Engineering, Stanford University, CA 94305-5025, USA
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