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Understanding the Mechanism of Starch Biosynthesis in Plants

English title Understanding the Mechanism of Starch Biosynthesis in Plants
Applicant Zeeman Samuel C.
Number 153144
Funding scheme Project funding (Div. I-III)
Research institution Departement Umweltsystemwissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Biochemistry
Start/End 01.04.2014 - 31.03.2017
Approved amount 474'000.00
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All Disciplines (2)

Discipline
Biochemistry
Botany

Keywords (6)

Saccharomyces cerevisiae; plant carbohydrate metabolism; synthetic biology; amylopectin; Arabidopsis thaliana; starch biosynthesis

Lay Summary (German)

Lead
Von Pflanzen produzierte Kohlenhydrate (Zucker und Stärke) bilden aufgrund ihres Nährwertes und Verwendung als industrieller Rohstoff eine bedeutende Grundlage unserer Gesellschaft. Dieses Projekt konzentriert sich auf die Stärkeherstellung. Mithilfe genetischer Methoden studieren wir die Bedeutung stärkesynthetisierender Enzyme in der Modellpflanze Arabidopsis thaliana, welche natürlicherweise Stärke produziert, und in der Hefe Saccharomyces cerevisiae, welche dies nicht tut. Außerdem untersuchen wir Pflanzenarten, die verschiedene Stärketypen herstellen.
Lay summary

Von Pflanzen produzierte Kohlenhydrate wie Zucker und Stärke bilden eine bedeutende Grundlage für unsere Gesellschaft: Sie besitzen nicht nur einen hohen Nährwert, sondern sind auch wichtige Rohstoffe für die Industrie und die Produktion von Biokraftstoffen, welche wahrscheinlich auch in Zukunft einen Teil unserer erneuerbaren Energien ausmachen werden.  Das Ziel der hier vorgeschlagenen Forschung ist es, zu verstehen, wie die Pflanze ihr häufigstes Speicherkohlenhydrat – Stärke – herstellt.

Stärke besteht aus Glukose (Traubenzucker), die zu linearen und verzweigten Ketten polymerisiert, welche dann wiederum semi-kristalline, wasserunlösliche Stärkekörner ausbilden. Obwohl Stärke uns allen bekannt ist, verstehen Wissenschaftler noch nicht vollständig, wie sie von Pflanzen hergestellt wird. Pflanzen besitzen zahlreiche spezielle Proteine – Enzyme –, die die Zuckerpolymere synthetisieren; nachwievor unbekannt ist jedoch, wie diese zusammenarbeiten, um die spezifische Struktur von Stärke zu erreichen. Um die Funktionen dieser Proteine in Modellpflanzen wie Arabidopsis thaliana und Nichtmodellpflanzen zu untersuchen, verwenden wir molekulargenetische sowie biochemische Methoden. Zum Beispiel entfernen wir einzelne oder mehrere Enzyme aus Arabidopsis thaliana und untersuchen dann die Auswirkungen auf die Stärkesynthese. Unser letztendliches Ziel ist es, Stärke nachzubauen, sei es im Reagenzglas oder in lebenden Zellen wie der Hefe Saccharomyces cerevisiae, die natürlicherweise keine herstellt. Dies würde zeigen, dass wir die Stärkesynthese verstehen. Zusätzlich wäre es ein nützliches Werkzeug, um unser Wissen, wie wir die Struktur der Stärke kontrollieren können, weiter zu erhöhen. Diese wertvollen Kenntnisse könnten dann dazu beitragen, verbesserte stärkeliefernde Pflanzen (wie Kartoffeln oder Getreide) herzustellen, entweder durch Züchtung oder durch biotechnologische Methoden.

Direct link to Lay Summary Last update: 05.03.2015

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Prof. R. Mezzenga Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. G Schertler/Paul Scherrer Institute Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Prof. A. Smith Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Dr. J. Lunn Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof B. Halkier/University of Copenhagen Denmark (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. A. Merida Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Invited talk at the CEA in Grenoble Individual talk New insights into starch metabolism from the analysis of non-enzymatic, starch binding proteins and from heterologous reconstruction of the biosynthetic pathway in yeast. 02.03.2017 Grenoble, France Zeeman Samuel C.;
Invited talk at the Max-Planck institute for Molecular Plant Physiology Individual talk Protein Targeting to STarch, a new class of proteins that bring enzymes and substrates together, and the heterologous reconstruction of the biosynthetic pathway in yeast 01.02.2017 Golm, Germany Zeeman Samuel C.;
European Starch Round Table Talk given at a conference New insights into starch metabolism from the analysis of non-enzymatic, starch binding proteins and from heterologous reconstruction of the biosynthetic pathway in yeast 17.11.2016 Lille, France Zeeman Samuel C.;
Minisymposium on the Application of Advanced Technologies for crop yield improvement Individual talk Starch Metabolism – from fundamental studies to improvement of our staple crops 27.09.2016 Ibadan, Nigeria Zeeman Samuel C.;
Norwegian Plant Biology Conference 2016 Talk given at a conference New Insights into Starch Metabolism 15.06.2016 Trondheim, Norway Zeeman Samuel C.;
Invited Speaker at the Ethiopian Institute of Agricultural Research Individual talk Discovering genetic determinants of starch structure for the improvement of tef and cassava 17.05.2016 Addis Abeba, Ethiopia Zeeman Samuel C.;
Annual Starch Convention Talk given at a conference Developing a yeast-based system for reconstruction the starch biosynthesis pathway 13.04.2016 Detmold, Germany Zeeman Samuel C.;
Annual Starch Convention Talk given at a conference Proteins that are important for amylose synthesis 13.04.2016 Detmold, Germany Zeeman Samuel C.;
Annual Meeting, Plant Biotech Denmark (PBD) Talk given at a conference Advancing our understanding of starch biosynthesis in plants: work in model species and pathway reconstruction in yeast 28.01.2015 Copenhagen, Denmark Zeeman Samuel C.;
Invited speaker at the University of Essex Individual talk New Insight into Starch Biosynthesis 14.11.2014 Colchester, Essex, Great Britain and Northern Ireland Zeeman Samuel C.;
2014 AACC International Annual Meeting Talk given at a conference Understanding starch biosynthesis in order to control its structure, composition and properties 05.10.2014 Providence, RI, United States of America Zeeman Samuel C.;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Invited talk at Carlsberg Laboratories Talk 23.02.2017 Copenhagen, Denmark Zeeman Samuel C.;
Invited talk at Minisymposium on the Application of Advanced Technologies for crop yield improvement, Intarnational Institute for Tropical Agriculture (CGIR) Talk 27.09.2016 Ibadan, Nigeria Zeeman Samuel C.;
Invited Speaker at KeyGene Talk 06.07.2016 Wageningen, Netherlands Zeeman Samuel C.;
Invited Speaker at the Ethiopian Institute of Agricultural Research Talk 17.05.2016 Addis Abeba, Ethiopia Zeeman Samuel C.;


Associated projects

Number Title Start Funding scheme
148857 Discovery of factors regulating carbohydrate storage in plants: implications for biotechnological improvement of crops for food and for clean, green technologies. 01.08.2014 Bilateral programmes
163503 Designing starch - harnessing carbohydrate polymer synthesis in plants 01.10.2015 ERA-CAPS
182570 Understanding the Cell Biology of Starch Metabolism in Plants 01.02.2019 Project funding (Div. I-III)
131074 Discovering the roles of debranching enzymes in starch metabolism in arabidopsis 01.04.2010 Project funding (Div. I-III)
170808 Acquisition of a Talos Arctica transmission electron microscope for single particle analysis and cryo-tomography 01.05.2017 R'EQUIP
166487 Multi-dimensional imaging to visualize starch biosynthesis in plants. 01.07.2016 Interdisciplinary projects

Abstract

The aim of this work is to understand how starch is synthesised in plants. Starch is the most abundant reserve carbohydrate in plants and a vital substance, being at the heart of human nutrition. Furthermore, it is a key renewable and versatile resource for industry. Starch forms insoluble granules that are composed two polymers of glucose; branched amylopectin, which makes up 70% or more of the starch, and amylose (a linear or lightly branched component). The branching pattern and chain length distribution of amylopectin enables it to form secondary and tertiary structures that result in the formation of a complex semi-crystalline matrix - the insoluble starch granule. The branching pattern of amylopectin also underlies some of the commercially important properties of starch.Genome sequence analysis has revealed that the enzymes of starch biosynthesis are highly conserved amongst vascular plants. These enzymes include five starch synthases, involved in initiating starch granules and elongating the glucan chains, two or more branching enzymes which introduce the branch points into amylopectin, and three debranching enzymes, one of which is particularly important in promoting the crystallisation of starch into insoluble granules. Work in recent years has greatly improved our understanding of the individual functions of these enzymes, but we still lack an understanding of how they work together in an interdependent way to generate a crystallisation-competent polymer.In the work described in this proposal, we will use a combination of methods to understand starch biosynthesis at a much deeper level. Firstly, we will continue our use of Arabidopsis molecular genetics to knock out combinations of starch biosynthetic genes, or overexpress endogenous/foreign genes. This wo¬rk will involve sound molecular biochemical and microscopic methods, in which we have proven expertise, and build on our existing knowledgebase. Secondly, we will pursue a synthetic biology approach, progressively engineering the yeast Saccharomyces cerevisiae via the introduction of Arabidopsis genes until we enable it to produce starch. Third, we will selectively employ state-of-the-art systems-biology (e.g. RNA-seq and shotgun proteomics) on Ryparrosa kurrangii , one of the very few plants that can make either glycogen or starch, to give novel insight into the reprogramming of starch biosynthetic genes, relate it to glucan structure. Finally, we will use 3-dimensional electron microscopy approaches (e.g. 3View serial sectioning and/or electron tomography) to obtain a much clearer picture of the physical organisation of starch biosynthesis within the plastids of plant cells. These approaches are complementary and together will help to help to complete our knowledge of the starch biosynthetic apparatus in plants.
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