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Unraveling transcriptional and translational control in plant energy homeostasis: A BIOINFORMATIC APPROACH Alessia Peviani Alessia Peviani (2016) Unraveling transcriptional and translational control in plant energy homeostasis: a bioinformatic approach. PhD thesis, Utrecht University Cover and layout by Alessia Peviani Printed by: PrintSupport4U (www.printsupport4u.nl) ISBN: 978-90-393-6584-7 Unraveling transcriptional and translational control in plant energy homeostasis: a bioinformatic approach Onderzoek naar transcriptionele en translationele controle van energie homeostase in planten: een bioinformatische studie (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof. dr. G. J. van der Zwaan, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 8 juli 2016 des middags te 4.15 uur door Alessia Peviani geboren op 23 april 1987 te Reggio Emilia, Italië Promotoren: Prof. dr. B. Snel Prof. dr. J.C.M. Smeekens Copromotor: Dr. S.J. Hanson The work presented in this thesis was financially supported by the European Union via the MERIT (MEtabolic Reprogramming by Induction of Transcription) Marie Curie Initial Training Network, grant agreement number 264474 under call FP7-PEOPLE-2010-ITN. 5 Table of Contents Chapter 1 ............................................................................................................... 8 General introduction Transcriptional control of energy homeostasis 11 The transcription factor ABI4 12 The C/S1 bZIP transcription factor network 13 Phylogenetics and comparative genomics approaches to the study of plant transcription factors 16 Translational control of energy homeostasis 22 Bioinformatic analysis of translationally regulated transcripts 25 Chapters outline 27 Chapter 2 .............................................................................................................. 28 ABI4: versatile activator and repressor Abstract 30 Results and discussion 30 The transcription factor ABI4 is evolutionarily conserved 30 Role in ABA signaling 32 The AP2 domain of ABI4 interacts with a specific DNA sequence 33 ABI4 acts as an activator and repression of gene expression 35 ABI4 activates and represses metabolic and developmental processes 35 Concluding remarks 39 Supplementary material 40 Chapter 3 .............................................................................................................. 46 The phylogeny of C/S1 bZIP transcription factors reveals a shared algal ancestry and the pre-angiosperm translational regulation of S1 transcripts Abstract 48 Introduction 48 Results 51 C and S1 bZIP subfamilies show lineage-specific patterns of gene duplications and losses in angiosperms 51 C and S bZIPs originated as sister groups before the emergence of land plants 53 In vivo reporter gene assays confirm 5’uORF-mediated SIRT in gymnosperms S1 bZIP orthologs 55 Discussion 57 6 A model for the early evolution of the C/S1 bZIP transcription factor network 58 A reference for comparative studies on C and S1 bZIPs in non-model species 60 Methods 60 Supplementary material 63 Chapter 4 .............................................................................................................. 64 Multiple sequence signals affect translational efficiency during sucrose treatment and seed germination in A. thaliana Abstract 66 Introduction 66 Results 69 Quantification of translationally regulated genes during sucrose treatment and seed germination 69 Translationally regulated transcripts show significant biases in length and GC content, but not in their codon usage 72 Enriched motifs differ in their distribution and localization across datasets 73 Structure signals correlate with translational regulation 75 Discussion 77 Both general and specific signals contribute to translational regulation 77 Condition-dependent changes in translational efficiency likely rely on multiple regulatory mechanisms 78 Conclusion 80 Methods 80 Supplementary material 84 Chapter 5 .............................................................................................................. 86 Summarizing discussion Phylogenetic analyses of plant transcription factors 88 Plant translational regulation 92 Concluding Remarks 94 References .......................................................................................................... 95 Samenvatting ............................................................................................................................................... 105 Curriculum Vitae .......................................................................................................................................... 107 List of publications ....................................................................................................................................... 108 Acknowledgements ..................................................................................................................................... 109 Description of photographic material 1 1 4 7 Chapter 1 9 1 General Introduction partially adapted from: The low energy signaling network Filipa Tomé1, Thomas Nägele2, Mattia Adamo3, Abhroop Garg4, Carles Marco-llorca4, Ella Nukarinen2, Lorenzo Pedrotti5, Alessia Peviani6, Andrea Simeunovic2, Anna Tatkiewicz7, Monika Tomar8, and Magdalena Gamm8 1Bayer CropScience NV, Innovation Center, Ghent, Belgium 2Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria 3Instituto Gulbenkian de Ciência, Oeiras, Portugal 4Zentrum für Molekularbiologie der Pflanzen, Eberhard Karls Universität Tübingen, Tübingen, Germany 5Julius-von-Sachs-Institut, Julius-Maximilians-Universität Würzburg, Würzburg, Germany 6Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands 7Universidad Politécnica de Madrid - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Centro de Biotecnología y Genómica de Plantas, Madrid, Spain 8Molecular Plant Physiology, Institute of Environmental Biology, Utrecht University, Utrecht, The Netherlands Frontiers in Plant Science 5, 353 (2014) 10 Chapter 1 ontrolling energy homeostasis is a challenge for all organisms, as they must constantly Csense and integrate internal and external signals to optimize growth and development, often under suboptimal conditions (Polge and Thomas 2007). This is particularly critical for plants which, being sessile organisms, are exposed to a changing environment without possibility of escaping or sheltering themselves. Unraveling the molecular regulatory systems responsible for plant energy homeostasis is an important first step to achieve significant advances in agricultural production, necessary to secure food resources for a growing world population subjected to the whims of climate change. Plants evolved complex signaling networks to finely coordinate energy consumption and preservation in all tissues (Baena-González et al. 2007; Baena-González 2010), which reflects into a distinctive regulatory genes repertoire when compared to other eukaryotes (Riechmann et al. 2000). Particularly during the evolution of land plants, several new families of transcription factors emerged, while others experienced a dramatic expansion, allowing for a more complex morphogenesis and adaptation to new environments (Shiu et al. 2005; Lang et al. 2010). In addition, post-transcriptional, translational, and post-translational mechanisms provide further levels in the fine-tuning of energy homeostasis. However, even for long-known and intensively studied processes much of the molecular effectors and mechanistic details are far from fully characterized, making necessary continuing efforts in fundamental research. Especially in recent years, more accessible high-throughput techniques have led to the production of vast amounts of molecular plant research data, such as full genomic sequences, transcript and metabolite levels in different experimental settings, transcription factors DNA-binding sites, protein-protein interaction affinities, and more. The concurrent growth of online repositories created the opportunity for the integrated computational analysis of a variety of biological data, making bioinformatic methods essential to extract higher-level information from independent experiments. This is reflected in the continuing development of computational tools for data visualization, analysis, and integration, including several specific to the plant biology domain (Mochida and Shinozaki 2011). One of the most significant advances is represented by the accessibility of newly sequenced plant genomes, which makes it possible to explore the evolution and conservation of gene families in much greater depth than previously possible. The work presented in this thesis investigates different energy-responsive systems in plants using a variety of bioinformatic approaches. The next two chapters focus on transcriptional control, investigating the evolutionary history of sugar-regulated transcription factors involved in seed development and stress response. In the last research chapter we move to translational control, analyzing the sequence features affecting the translational efficiency of certain transcripts during seed germination and sucrose treatment. The following paragraphs introduce the regulatory systems and bioinformatic approaches described in later chapters, to make the reader familiar with the content of this thesis.