DOCSLIB.ORG

Computational Analysis and Manipulation of the Metabolic Network of Drug Producing Microorganisms

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Computational Analysis and Manipulation of the Metabolic Network of Drug Producing Microorganisms Computational analysis and manipulation of the metabolic network of drug producing microorganisms INAUGURALDISSERTATION zur Erlangung des Doktorgrades der Fakultät für Chemie und Pharmazie der Albert-Ludwigs-Universität Freiburg im Breisgau Vorgelegt von Dennis Klementz aus Wiesbaden-Dotzheim Freiburg 2017 Dekan: Prof. Dr. Manfred Jung Vorsitzender des Promotionsausschusses: Prof. Dr. Stefan Weber Referent: Prof. Dr. Stefan Günther Korreferent: Prof. Dr. Andreas Bechthold Drittprüfer: Prof. Dr. Oliver Einsle Datum der Promotion: 26.02.2018 “What we observe is not nature itself, but nature exposed to our method of questioning.” Werner Heisenberg Index Index 1 Abstract ......................................................................................................................... 1 2 Introduction ................................................................................................................... 3 2.1 Streptomycetes, an important source of natural drugs .................................................... 3 2.2 Nucleocidin production in Streptomyces calvus ............................................................... 6 2.3 Griseorhodin A, a telomerase inhibitor from a marine Streptomyces strain .................... 9 2.4 Genome-scale metabolic modeling and Flux Balance Analysis ....................................... 11 2.5 ‘Omics’ data and genome-scale metabolic models ......................................................... 14 2.6 Enhanced secondary metabolite production and genome-scale metabolic models ...... 16 3 Materials ....................................................................................................................... 19 3.1 Chemicals ......................................................................................................................... 19 3.2 Equipment ....................................................................................................................... 21 3.3 Consumables .................................................................................................................... 23 3.4 Strains .............................................................................................................................. 24 3.5 Programs & Services ........................................................................................................ 25 3.6 Cultivation media ............................................................................................................. 26 3.6.1 TSB (Tryptone Soy Broth) ......................................................................................... 26 3.6.2 MS (Mannitol Soy) .................................................................................................... 26 3.6.3 SG+ (Soytone Glucose) .............................................................................................. 26 3.6.4 Minor Element Solution ........................................................................................... 27 3.6.5 Buffer ........................................................................................................................ 27 3.6.6 Minimal medium ...................................................................................................... 27 Index 4 Methods ....................................................................................................................... 28 4.1 StreptomeDB ................................................................................................................... 28 4.1.1 Data collection .......................................................................................................... 28 4.1.2 Genomes, taxonomy and gene clusters ................................................................... 28 4.1.3 Generation of the phylogenetic tree ....................................................................... 28 4.2 AdpA in Streptomyces asterosporus ............................................................................... 30 4.2.1 Detection of transposons ......................................................................................... 30 4.2.2 Detection of adpA binding sites ............................................................................... 30 4.2.3 Prediction of adpA regulon ...................................................................................... 30 4.2.4 Potential disrupted genes ........................................................................................ 30 4.2.5 G+C content and skew.............................................................................................. 31 4.2.6 Dotplot ...................................................................................................................... 31 4.3 Genome-scale metabolic modeling ................................................................................. 32 4.3.1 Model reconstruction ............................................................................................... 32 4.3.2 Analysis of essential elements ................................................................................. 32 4.3.3 Correlation plot and area under the curve (AUC) .................................................... 32 4.3.4 Knockout candidate identification ........................................................................... 33 4.3.5 Integration of transcriptomic data ........................................................................... 34 4.3.6 Generation of functional subsets ............................................................................. 35 4.3.7 Minimal medium prediction and validation ............................................................. 35 4.4 Strain cultivation .............................................................................................................. 36 4.4.1 Preculture ................................................................................................................. 36 4.4.2 Permanent culture ................................................................................................... 36 4.4.3 Agar cultures ............................................................................................................ 36 Index 4.4.4 Liquid culture in Erlenmeyer flasks .......................................................................... 36 4.4.5 Dry weight measurement ......................................................................................... 36 4.4.6 Sample preparation for HPLC-MS ............................................................................ 37 4.4.7 HPLC measurement .................................................................................................. 37 5 Results .......................................................................................................................... 38 5.1 StreptomeDB update ....................................................................................................... 38 5.2 Data Overview ................................................................................................................. 38 5.3 Phylogenetic tree ............................................................................................................. 43 5.3.1 NMR and MS prediction ........................................................................................... 45 5.3.2 Scaffold browser ....................................................................................................... 47 5.4 bldA function in Streptomyces calvus ............................................................................. 49 5.4.1 Metabolic model ...................................................................................................... 49 5.4.2 Gene expression ....................................................................................................... 50 5.4.3 Protein production ................................................................................................... 61 5.5 Role of adpA function in Streptomyces asterosporus ..................................................... 67 5.5.1 Genome Overview .................................................................................................... 67 5.5.2 Putative disrupted genes ......................................................................................... 70 5.5.3 Proteomic analysis ................................................................................................... 73 5.6 Enhancement of Griseorhodin A production in Streptomyces avermitilis SUKA22 ........ 75 5.6.1 Metabolic model ...................................................................................................... 75 5.6.2 Minimal-medium validation experiment ................................................................. 76 5.6.3 Knockout candidate identification ........................................................................... 79 5.6.4 Overview of all knockout candidates ..................................................................... 112 5.7 Experimental results ...................................................................................................... 114 Index 6 Discussion & Conclusion .............................................................................................. 118 6.1 StreptomeDB ................................................................................................................. 118 6.2 The effect of bldA in Streptomyces calvus....................................................................
Load more

Recommended publications
  • Study of Actinobacteria and Their Secondary Metabolites from Various Habitats in Indonesia and Deep-Sea of the North Atlantic Ocean
    Study of Actinobacteria and their Secondary Metabolites from Various Habitats in Indonesia and Deep-Sea of the North Atlantic Ocean Von der Fakultät für Lebenswissenschaften der Technischen Universität Carolo-Wilhelmina zu Braunschweig zur Erlangung des Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigte D i s s e r t a t i o n von Chandra Risdian aus Jakarta / Indonesien 1. Referent: Professor Dr. Michael Steinert 2. Referent: Privatdozent Dr. Joachim M. Wink eingereicht am: 18.12.2019 mündliche Prüfung (Disputation) am: 04.03.2020 Druckjahr 2020 ii Vorveröffentlichungen der Dissertation Teilergebnisse aus dieser Arbeit wurden mit Genehmigung der Fakultät für Lebenswissenschaften, vertreten durch den Mentor der Arbeit, in folgenden Beiträgen vorab veröffentlicht: Publikationen Risdian C, Primahana G, Mozef T, Dewi RT, Ratnakomala S, Lisdiyanti P, and Wink J. Screening of antimicrobial producing Actinobacteria from Enggano Island, Indonesia. AIP Conf Proc 2024(1):020039 (2018). Risdian C, Mozef T, and Wink J. Biosynthesis of polyketides in Streptomyces. Microorganisms 7(5):124 (2019) Posterbeiträge Risdian C, Mozef T, Dewi RT, Primahana G, Lisdiyanti P, Ratnakomala S, Sudarman E, Steinert M, and Wink J. Isolation, characterization, and screening of antibiotic producing Streptomyces spp. collected from soil of Enggano Island, Indonesia. The 7th HIPS Symposium, Saarbrücken, Germany (2017). Risdian C, Ratnakomala S, Lisdiyanti P, Mozef T, and Wink J. Multilocus sequence analysis of Streptomyces sp. SHP 1-2 and related species for phylogenetic and taxonomic studies. The HIPS Symposium, Saarbrücken, Germany (2019). iii Acknowledgements Acknowledgements First and foremost I would like to express my deep gratitude to my mentor PD Dr.
    [Show full text]
  • Genomic and Phylogenomic Insights Into the Family Streptomycetaceae Lead to Proposal of Charcoactinosporaceae Fam. Nov. and 8 No
    bioRxiv preprint doi: https://doi.org/10.1101/2020.07.08.193797; this version posted July 8, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Genomic and phylogenomic insights into the family Streptomycetaceae 2 lead to proposal of Charcoactinosporaceae fam. nov. and 8 novel genera 3 with emended descriptions of Streptomyces calvus 4 Munusamy Madhaiyan1, †, * Venkatakrishnan Sivaraj Saravanan2, † Wah-Seng See-Too3, † 5 1Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 6 Singapore 117604; 2Department of Microbiology, Indira Gandhi College of Arts and Science, 7 Kathirkamam 605009, Pondicherry, India; 3Division of Genetics and Molecular Biology, 8 Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, 9 Malaysia 10 *Corresponding author: Temasek Life Sciences Laboratory, 1 Research Link, National 11 University of Singapore, Singapore 117604; E-mail: [email protected] 12 †All these authors have contributed equally to this work 13 Abstract 14 Streptomycetaceae is one of the oldest families within phylum Actinobacteria and it is large and 15 diverse in terms of number of described taxa. The members of the family are known for their 16 ability to produce medically important secondary metabolites and antibiotics. In this study, 17 strains showing low 16S rRNA gene similarity (<97.3 %) with other members of 18 Streptomycetaceae were identified and subjected to phylogenomic analysis using 33 orthologous 19 gene clusters (OGC) for accurate taxonomic reassignment resulted in identification of eight 20 distinct and deeply branching clades, further average amino acid identity (AAI) analysis showed 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.07.08.193797; this version posted July 8, 2020.
    [Show full text]
  • Emerging Strategies and Integrated Systems Microbiology Technologies for Biodiscovery of Marine Bioactive Compounds
    Mar. Drugs 2014, 12, 3516-3559; doi:10.3390/md12063516 OPEN ACCESS marine drugs ISSN 1660-3397 www.mdpi.com/journal/marinedrugs Review Emerging Strategies and Integrated Systems Microbiology Technologies for Biodiscovery of Marine Bioactive Compounds Javier Rocha-Martin 1, Catriona Harrington 1, Alan D.W. Dobson 2,3 and Fergal O’Gara 1,2,3,4,* 1 BIOMERIT Research Centre, School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland; E-Mails: [email protected] (J.R.-M.); [email protected] (C.H.) 2 School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland; E-Mail: [email protected] 3 Marine Biotechnology Centre, Environmental Research Institute, University College Cork, National University of Ireland, Cork, Ireland 4 School of Biomedical Sciences, Curtin University, Perth, WA 6102, Australia * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +353-21-490-2646; Fax: +353-21-427-5934. Received: 8 April 2014; in revised form: 21 May 2014 / Accepted: 22 May 2014 / Published: 10 June 2014 Abstract: Marine microorganisms continue to be a source of structurally and biologically novel compounds with potential use in the biotechnology industry. The unique physiochemical properties of the marine environment (such as pH, pressure, temperature, osmolarity) and uncommon functional groups (such as isonitrile, dichloroimine, isocyanate, and halogenated functional groups) are frequently found in marine metabolites. These facts have resulted in the production of bioactive substances with different properties than those found in terrestrial habitats. In fact, the marine environment contains a relatively untapped reservoir of bioactivity. Recent advances in genomics, metagenomics, proteomics, combinatorial biosynthesis, synthetic biology, screening methods, expression systems, bioinformatics, and the ever increasing availability of sequenced genomes provides us with more opportunities than ever in the discovery of novel bioactive compounds and biocatalysts.
    [Show full text]
  • Evolution of Cyclizing 5-Aminolevulinate Synthases in the Biosynthesis of Actinomycete Secondary Metabolites: Outcomes For
    ORIGINAL RESEARCH published: 05 August 2015 doi: 10.3389/fmicb.2015.00814 Evolution of cyclizing 5-aminolevulinate synthases in the biosynthesis of actinomycete secondary metabolites: outcomes for Edited by: genetic screening techniques Eric Altermann, 1 2 1 2 AgResearch Ltd, New Zealand Katerinaˇ Petríˇ ckovᡠ, Alica Chronákovᡠ*,TomášZelenka ,TomášChrudimský , Stanislav Pospíšil1, Miroslav Petríˇ cekˇ 1* and Václav Krišt ˚ufek2 Reviewed by: Suleyman Yildirim, 1 Institute of Microbiology, Czech Academy of Sciences, v. v. i., Prague, Czech Republic, 2 Institute of Soil Biology, Biology Istanbul Medipol University, Turkey Centre, Czech Academy of Sciences, v. v. i., Ceskéˇ Budejovice,ˇ Czech Republic Polpass Arul Jose, Tamil Nadu Agricultural University, India A combined approach, comprising PCR screening and genome mining, was used to Virginia Helena Albarracín, unravel the diversity and phylogeny of genes encoding 5-aminolevulinic acid synthases PROIMI – CONICET, Argentina *Correspondence: (ALASs, hemA gene products) in streptomycetes-related strains. In actinomycetes, Miroslav Petˇrícek,ˇ these genes were believed to be directly connected with the production of Institute of Microbiology, Czech secondary metabolites carrying the C5N unit, 2-amino-3-hydroxycyclopent-2-enone, Academy of Sciences, v. v. i., Vídenskᡠ1083, 142 20 Prague, with biological activities making them attractive for future use in medicine and agriculture. Czech Republic Unlike “classical” primary metabolism ALAS, the C5N unit-forming cyclizing ALAS [email protected]; (cALAS) catalyses intramolecular cyclization of nascent 5-aminolevulinate. Specific Alica Chronáková,ˇ Institute of Soil Biology, Biology amino acid sequence changes can be traced by comparison of “classical” ALASs Centre, Czech Academy of Sciences, against cALASs. PCR screening revealed 226 hemA gene-carrying strains from 1,500 v.
    [Show full text]
  • Phylogenetic Study of the Species Within the Family Streptomycetaceae
    Antonie van Leeuwenhoek DOI 10.1007/s10482-011-9656-0 ORIGINAL PAPER Phylogenetic study of the species within the family Streptomycetaceae D. P. Labeda • M. Goodfellow • R. Brown • A. C. Ward • B. Lanoot • M. Vanncanneyt • J. Swings • S.-B. Kim • Z. Liu • J. Chun • T. Tamura • A. Oguchi • T. Kikuchi • H. Kikuchi • T. Nishii • K. Tsuji • Y. Yamaguchi • A. Tase • M. Takahashi • T. Sakane • K. I. Suzuki • K. Hatano Received: 7 September 2011 / Accepted: 7 October 2011 Ó Springer Science+Business Media B.V. (outside the USA) 2011 Abstract Species of the genus Streptomyces, which any other microbial genus, resulting from academic constitute the vast majority of taxa within the family and industrial activities. The methods used for char- Streptomycetaceae, are a predominant component of acterization have evolved through several phases over the microbial population in soils throughout the world the years from those based largely on morphological and have been the subject of extensive isolation and observations, to subsequent classifications based on screening efforts over the years because they are a numerical taxonomic analyses of standardized sets of major source of commercially and medically impor- phenotypic characters and, most recently, to the use of tant secondary metabolites. Taxonomic characteriza- molecular phylogenetic analyses of gene sequences. tion of Streptomyces strains has been a challenge due The present phylogenetic study examines almost all to the large number of described species, greater than described species (615 taxa) within the family Strep- tomycetaceae based on 16S rRNA gene sequences Electronic supplementary material The online version and illustrates the species diversity within this family, of this article (doi:10.1007/s10482-011-9656-0) contains which is observed to contain 130 statistically supplementary material, which is available to authorized users.
    [Show full text]
  • Diversity and Versatility of Actinomycetes and Its Role in Antibiotic Production
    Journal of Applied Pharmaceutical Science Vol. 3 (8 Suppl 1), pp. S83-S94, September, 2013 Available online at http://www.japsonline.com DOI: 10.7324/JAPS.2013.38.S14 ISSN 2231-3354 Diversity and Versatility of Actinomycetes and its Role in Antibiotic Production Hotam Singh Chaudhary, Bhavana Soni, Anju Rawat Shrivastava, Saurabh Shrivastava Madhav Institute of Technology & Science, Gwalior – 474005, India. ARTICLE INFO ABSTRACT Article history: This review summarizes about the actinomycetes and their capability to produce bioactive secondary metabolites, Received on: 06/06/2013 many of which have been successfully isolated and turned into useful drugs and other organic chemicals. Revised on: 27/06/2013 Microbial pathogens are becoming increasingly resistant to available treatments so new antibiotics are needed, Accepted on: 14/08/2013 but the channel of compounds under development is scarce. There is frantic need of new microbial agents to fight Available online: 18/09/2013 against the antibiotic resistant strains of pathogenic microorganisms, which are rapidly increasing gradually. Therefore, actinomycetes hold a prominent position due to their diversity and proven ability to produce new Key words: bioactive compounds predominantly used in antibiotic production. A critical element in a drug discovery based Metabolites, on microbial extracts is the isolation of unexploited groups of microorganisms that are at the same time good immunosuppressive, producers of secondary metabolites. Few of the antibiotics produced by actinomycetes are included in this review bioactive compound, along with their activities to prove the versatility of this powerful microbial organism. Many ecological niches actinomycetes. still remain unexplored yet which needs to be studied for a greater diversity of novel actinomycetes.
    [Show full text]
  • From a Natural Product to Its Biosynthetic Gene Cluster: a Demonstration Using Polyketomycin from Streptomyces Diastatochromogenes Tü6028
    Journal of Visualized Experiments www.jove.com Video Article From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028 Anja Greule1, Songya Zhang1, Thomas Paululat2, Andreas Bechthold1 1 Department of Pharmaceutical Biology and Biotechnology, Albert-Ludwigs-Universität Freiburg, Germany 2 Department of Chemistry and Biology, Universität Siegen Correspondence to: Andreas Bechthold at [email protected] URL: https://www.jove.com/video/54952 DOI: doi:10.3791/54952 Keywords: Genetics, Issue 119, natural products, polyketomycin, Streptomyces diastatochromogenes Tü6028, extraction, purification, HPLC, biosynthetic gene cluster, genome sequencing, genome mining, single crossover. Date Published: 1/13/2017 Citation: Greule, A., Zhang, S., Paululat, T., Bechthold, A. From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028. J. Vis. Exp. (119), e54952, doi:10.3791/54952 (2017). Abstract Streptomyces strains are known for their capability to produce a lot of different compounds with various bioactivities. Cultivation under different conditions often leads to the production of new compounds. Therefore, production cultures of the strains are extracted with ethyl acetate and the crude extracts are analyzed by HPLC. Furthermore, the extracts are tested for their bioactivity by different assays. For structure elucidation the compound of interest is purified by a combination of different chromatography methods. Genome sequencing coupled with genome mining allows the identification of a natural product biosynthetic gene cluster using different computer programs. To confirm that the correct gene cluster has been identified, gene inactivation experiments have to be performed. The resulting mutants are analyzed for the production of the particular natural product.
    [Show full text]
  • Genomics, Proteomics and Secondary Metabolites Biosynthesis Research on Streptomyces Asterosporus DSM 41452
    - 1 - Genomics, Proteomics and Secondary Metabolites Biosynthesis Research on Streptomyces asterosporus DSM 41452 Dissertation zur Erlangung des Doktorgrades der Fakultät für Chemie und Pharmazie der Albert-Ludwigs-Universität Freiburg im Breisgau Vorgelegt von Songya Zhang Aus Zhengzhou, China 2018 - 2 - Dekan: Prof. Dr. Manfred Jung Vorsitzender des Promotionsausschusses: Prof. Dr. Stefan Weber Referent: Prof. Dr. Andreas Bechthold Korreferent: Prof. Dr. Irmgard Merfort Drittprüfer: Prof. Dr. Oliver Einsle Datum der Promotion: 20.04.2018 - 3 - Erklärung Hiermit erkläre ich, dass ich die vorliegende Arbeit selbstständig und nur unter Verwendung der angegebenen Literatur und Hilfsmittel angefertigt sowie Zitate kenntlich gemacht habe. - 4 - Acknowledgements I would like to take this opportunity to express my appreciation to my supervisor, Prof. Dr. Andreas Bechthold, for his support, encouragement and guidance throughout my study in this outstanding research environment at the Fakultät für Chemie und Pharmazie in Freiburg University. His enthusiasm and attitude towards science and research will definitely affect my life. I am particularly thankful to my co-advisor Prof. Dr. Irmgard Merfort for kindly reviewing this thesis, her generous help during my study, for being the supervisor of my doctoral committee. I desire to convey my earnest appreciation to Prof. Dr. Oliver Einsle for being the member of my doctoral committee. In addition, I feel grateful to Dr. Lin Zhang for his help to determine protein structure and professional advice on my research project. I would also wish to thank Prof. Dr. Stefan Günther for reviewing the manuscript. I also want to express my greatest thanks to Dennis Klementz for his reliable help in terms of bioinformatics analysis and for helping revise my manuscript.
    [Show full text]
  • Chapter 4 Engineering of Streptomyces Lividans For
    Engineering of Streptomyces albus J1074 and Streptomyces lividans TK24 for Natural Products Production Dissertation zur Erlangung des Grades des Doktors der Naturwissenschaften der Naturwissenschaftlich-Technischen Fakultät der Universität des Saarlandes Von Yousra Ahmed Saarbrücken 2019 2 Tag des Kolloquiums: 09. August 2019 Dekan: Prof. Dr. rer. nat. Guido Kickelbick Berichterstatter: Prof. Dr. Andriy Luzhetskyy Prof. Dr. Rolf Müller Vorsitz: Prof. Dr. Volkhard Helms Akad. Mitarbeiter: Dr. Stefan Boettcher 3 Diese Arbeit entstand unter der Anleitung von Prof. Dr. Andriy Luzhetskyy in der Fachrichtung Pharmazeutische Biotechnologie der Naturwissenschaftlich-Technischen Fakultät der Universität des Saarlandes von Mai 2013 bis August 2018. 4 Acknowledgement Acknowledgments Firstly, I would like to express my deep sense of gratitude and respectful regards to my supervisor Prof. Dr. Andriy Luzhetskyy for giving me the opportunity to work in his group on these exciting projects. I highly appreciate his invaluable guidance and continuous support throughout my PhD studies. I am also thankful to him for reading the manuscript of this thesis and for his recommendations to improve it. I would like to thank Prof. Dr. Rolf Müller for his insightful comments and suggestions during the committee meetings and for being the second reviewer of this thesis. I am forever grateful to Dr. Yuriy Rebets, my lab supervisor, for his patience, motivation, and for sparing his valuable time whenever I needed. His useful experimental advice, constructive suggestions and scientific inspiration made it possible for me to achieve my goal. I am indebted to him for his help, suggestions and correction of the entire thesis. It has been an absolute pleasure to work with and learn from him.
    [Show full text]
  • Osaka University Knowledge Archive : OUKA
    Activation and characterization of cryptic Title phthoxazolin A biosynthetic gene cluster in Streptomyces avermitilis Author(s) Suroto, Dian Anggraini Citation Issue Date Text Version ETD URL https://doi.org/10.18910/70676 DOI 10.18910/70676 rights Note Osaka University Knowledge Archive : OUKA https://ir.library.osaka-u.ac.jp/ Osaka University Doctoral Dissertation Activation and characterization of cryptic phthoxazolin A biosynthetic gene cluster in Streptomyces avermitilis (Streptomyces avermitilis におけるﾌトキサソﾞリ A 休眠生合成遺伝群の活性化および機能解析) DIAN ANGGRAINI SUROTO April 2018 Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University i Table of Contents Table of Contents ii List of Figures v List of Tables vii Abbreviations viii Chapter 1. General Introduction 1 1.1.The habitat and life cycle of Streptomyces 1 1.2.Production of secondary metabolites in Streptomyces 3 1.2.1 .The assembly line of polyketides 5 1.2.2. The assembly line of nonribosomal peptides 9 1.3.Regulation of secondary metabolites production in Streptomyces 10 1.3.1. Nutrients availability 10 1.3.2. The hierarchical regulatory networks 11 1.3.3.The autoregulator signaling molecules and the autoregulatory cascade 13 1.3.3.1. Structural classification of autoregulators 13 1.3.3.2. The receptor proteins in autoregulator signaling cascade 15 1.4. Cryptic secondary metabolisms in Streptomyces 17 1.5. Strategies for activation of cryptic secondary metabolisms 18 1.5.1. Alteration of cultivation condition 18 1.5.2. Ribosome engineering 20 1.5.3. Alteration of the regulatory networks 20 1.5.4. Genome mining and heterologous expression 22 1.6. Streptomyces avermitilis 24 1.7.Overview and objectives of the study 27 Chapter 2.
    [Show full text]