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Research Interests

See below for PhD project opportunities. NEW! Links to FindaPhD projects molecular switches; phytopharmacology and Polar Auxin Transport; clathrin cages.

Hormone recognition, binding and selectivity

The auxin receptor TIR1 and the related AFBs are expressed from insect cells and binding is explored in terms of kinetics (surface plasmon resonance, Biacore), thermodynamics (isothermal titration calorimetry, ITC) and structure. This project is joint with Dr Stefan Kepinski (University of Leeds, UK). It is known that auxin completes a nascent substrate binding pocket as it binds to TIR1. The substrates are the Aux/IAA transcriptional regulators which, on binding, become ubiquitinated through the ubiquitin E3 ligase activity of TIR1. We are exploring how selectivity is conferred for different auxins and different Aux/IAAs, and how these two variables affect each other. We are building pharmacophoric maps of auxin receptors in order to inform rational design and selection of novel auxins and anti-auxins.

Auxin transport proteins, phytopharmacology and Polar Auxin Transport

We are starting to examine auxin transport proteins with the same degree of molecular precision. We recently published a pharmacophoric map of the auxin uptake carrier AUX1, reviewed the biochemistry of AUX1, and presented a model of PIN2.

Biosensors

Biosensors, like receptor proteins, need to recognise analytes with appropriate sensitivity and selectivity. The group is developing hormone sensor domains in order to generate experimental plant hormone biosensors. We are working with Prof Nick Dale (University of Warwick), a neurobiologist and specialist in the development of purine biosensors, to develop a microelectrode-based biosensor for cytokinins. This work is in collaboration with Prof Ivo Frebort (University of Olomouc).

E-noses in agriculture

Electronic devices for detecting volatiles have developed rapidly and small, portable and highly sensitive deveices are available for a wide range of applications. Communication via volatiles is commonplace in nature and I am interested in applying e-noses as real-time sensors for biological responses for the benefit of agriculture. This work is in collaboration with Dr James Covington (School of Engineering, University of Warwick).

PhD Projects available:

Check here for funding opportunities and scholarship schemes and Warwick Chancellor’s International Scholarship scheme

DNA Tetrahedra as Sensors – nanotechnology platforms for plants.

DNA tetrahedra are formed in a single step from four component strands. The assembly process is straightforward and high-yielding, making them attractive for nanotechnology applications. In addition, the 3’ and 5’ ends of the strands can be moved around the structure to achieve a high degree of control over the placement of functional groups – for example fluorophores. Their size and likely stability suggest they may be perfect vehicles for novel nanobiosensors.

Contact richard.napier@warwick.ac.uk

Evolution of hormone-activated molecular switches. A project with Dr Charo del Genio (Dept of Physics, University of Coventry) and Prof Phillip Stansfeld (Life Sciences, Warwick). Crystal structures for two hormone-activated molecular switches are available, the related F-box proteins TIR1 and COI1. Each protein binds different small molecule hormones in a deep pocket to create a binding site for a transcription factor for control over gene expression. The receptors have evolved from a common ancestor and you will reconstruct hypothetical ancestral intermediate receptors to understand how specificity for the two hormones evolved. The results will help us understand the molecular basis of recognition and will form the basis of designing new molecular switches. Contact richard.napier@warwick.ac.uk

Gathering cargo for endocytosis using TPLATE. A project with Dr Corinne Smith (cryo-EM), Dr Alex Jones (proteomics) and Prof Tim Dafforn (University of Birmingham; nanoencapsulation).

This project will reveal the structural interactions necessary for managing polarity in plant cellular organisation. Clathrin-mediated endocytosis underpins the orderly cycling and recycling of membrane components. Cargo recruitment uses adaptor protein complexes and the TPLATE complex is specific to the plant kingdom. A series of technological advances now allow the project team to purify native TPLATE complexes and selectively purify the subset which contain the auxin-transporting PIN proteins. We will solve the structure of the PIN-TPLATE complex using high resolution cryo-electron microscopy.

Contact richard.napier@warwick.ac.uk

Pharmacological profiling and structural analysis of the PIN auxin transport proteins: a project with Dr Alex Cameron (Life Sciences, Warwick) and Dr Mark Wall (Life Sciences, Warwick). We express PIN proteins in tissue culture. These transporters determine some of the most profound morphogenic events in biology, such as polarity in the embryo, and yet we have no mechanistic understanding of how they work. Cultures expressing PINs will be used with the patch clamp technique to record the pharmacological activity profiles of substrates and inhibitors. Cell cultures will also provide protein for purification and crystallisation in order to determine the structure of these vital transport proteins by crystallography.

Contact richard.napier@warwick.ac.uk