Principal Supervisor name and department: Dr. Jose Gutierrez-Marcos, SLS Second Supervisor name and department: Dr. Ann Dixon, Chemistry Where will the student be based? Chemistry) Split between two departments (60% SLS and 40% PhD project title: Regulation of early embryo development by extra-embryonic secreted peptides Project description: Although much is known about the role of non-peptide hormones in regulating growth and development in animals and plants, relatively little is known about the significant role played by small signalling peptides in regulating such processes. Recently, an increasingly large number of genes encoding small, secreted peptides in animals and plants have been implicated in mediating cell–cell interactions. For example, there are demonstrated roles for peptide signals in defence responses, cell proliferation and differentiation, maintenance of stem cell identity, and in reproduction. Although both genetic and biochemical methods have thus far been used to identify and characterise such peptides, we remain ignorant of their biophysical properties and how their physical structure relates to function and performance. This project aims to establish a link between the physical and chemical properties of a group of newly identified peptide ligands that regulate early embryogenesis in plants. Surprisingly, these peptides are secreted from extra-embryonic tissues and interact with a discrete class of transmembrane receptors to regulate the asymmetric division of the zygote. Therefore the principal aim of this project is to decipher how these peptides mediate such specific developmental response in early embryos. Key experimental skills involved: The student will carry out a series of experiments designed to determine the peptide structure and the interactions with transmembrane receptors. Analytical ultracentrifugation (AUC) will be used to determine protein size, shape and oligomeric state, as well as key thermodynamic properties including the free energy of dissociation for any SCR oligomers and complexes formed. Protein nuclear magnetic resonance (NMR) methodologies will also be used to confirm the first highresolution solution state structures of these proteins. NMR methods could also provide information of the dynamics of these proteins and their interactions with other key ligands and proteins. Complementing these techniques, mutagenesis in combination with in vivo and invitro genetic complementation assays will provide information on the biological significance of the peptides. Because these peptides share striking homology to other secreted peptides found in distantly related plant species, it is envisaged that this project will become a template for future analyses in crop plant species. References: Costa LM, Yuan J, Rouster J, Paul W, Dickinson H, Gutierrez-Marcos JF. (2012) Maternal control of nutrient allocation in plant seeds by genomic imprinting. Current Biology 24;22(2):160-5. Ohki S, Makoto T, and M Mori (2011) The NMR structure of stomagen reveals the basis of stomatal density regulation by plant peptide hormones. Nature Communincation 2; 512-515 Contact details for application enquiries: Jose Gutierrez-Marcos, Email: J.F.Gutierrez-Marcos@warwick.ac.uk Keywords: cell-cell communication, signalling, peptide, NMR, structure Please state below which hazards may be connected with this studentship: The studentship will entail work involving: Chemicals – high toxicity and category 1 or 2 substances Organo-phosphate or carbamate pesticides √ if applies N/A N/A N/A Skin or respiratory sensitising agents (e.g. insect parts, organic dusts from animals, spores, pollen, antibiotics, fibres, chemical sensitisers, wood dust etc) Radionuclides Significant manual handling Mechanical repetition where the frequency and duration are significant Working in areas where there are temperature extremes Driving vehicles (tractors, fork lifts, ATVs etc) Crop planting, harvesting, recording or grading Working in close proximity to bees or other stinging insects Working at height [>2 m] (using various types of access equipment) Working with noisy or vibrating equipment Working at night (between 11.00pm and 6.00am) Food handling √ N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Other significant hazards (specify)