Graduate Teaching Assistantship

This is a Graduate Training Assistantship (GTA), which means that you will be required to do some teaching, particularly lab demonstrating, as part of your training. GTAs allow research students to fund their PhD through part-time teaching work with the University.

Approximately 80% of your time will be spent on doctoral research leading to a PhD and 20% on GTA responsibilities. Training is provided to help Graduate Teaching Assistants develop their teaching related skills and enhance their professional competencies.

Project Description

Project Highlights

The interaction of haem with the protein, PERIOD, which plays an essential role in maintain 24 hr patterns in human physiology, will be invested using biophysical approaches.

The main techniques used in this research project will be fluorescence lifetime spectroscopy and imaging, nuclear magnetic resonance spectroscopy and isothermal calorimetry.

The successful student will also be trained in experimental approaches in chemical biology, essential for a research career at the interface between chemistry and biology.

Project

Haem is a small organic molecule containing iron at the centre. No eukaryote has ever been identified that can survive without heme. Thousands of different proteins are known in which a heme molecule is an integral component, and these are responsible for processes such as oxygen transport, electron transfer, respiration, metabolism of drugs, and all kinds of catalysis across the whole of the biological world. It is an amazing feat of Nature that such a simple molecule is pivotal to such a wide range of cellular biology, but it has emerged recently that this is just the tip of a much bigger iceberg. The recent literature describes an entirely new portfolio of other, more complicated, biological processes that are characterised by weaker (or transient) interactions between heme and protein ligands. In these examples, the heme group is not pivotal to the functional activity of the protein but is required intermittently to modulate protein behaviour via reversible binding to Lewis bases on the side chains of certain amino acid residues (usually cysteines or histidines). Mechanisms for these interactions can be explained using the models for ligand-substitution reactions in transition-metal complexes. In this case, the sites of ligand transfer are the axial positions in the heme (Fe-protoporphyrin IX) complex.

Our interest lies in a protein, called PERIOD, that plays a role in maintaining the rhythmic 24hr-pattern of the biological clock. Haem is able to bind to PERIOD at two locations on the proteins, however, we do not understand why this has an effect on the activity of PERIOD in the molecular mechanism of the circadian clock. Our hypothesis is that the binding interaction with haem leads to a significant change in the conformational structure of the protein, which blocks its function. This hypothesis will be tested in the research project.

The aims of the research work will be to characterise the interaction between haem and the protein, PERIOD, and any subsequent structural changes in the protein between the apo (haem free) and holo (haem bound) states. The activity of PERIOD is contingent on its formation of a heterodimer with another protein called CRYPTOCHROME, and so we will investigate how the interaction between these two proteins changes in the presence of haem.

The project work will involve biophysical measurements of haem binding to PERIOD using both isothermal calorimetry and biolayer interferometry. Characterisation of the conformational dynamics of the protein using fluorescence lifetime spectroscopy and structural studies using nuclear magnetic resonance spectroscopy and X Ray crystallography. Training will also be provided in protocols for protein expression and purification.

By understanding how haem interferes with the activity of this circadian protein and its protein-protein interactions, we will uncover a facet of the regulatory role of haem, which extends far beyond gene transcription to the immune response, neurodegeneration and aging, gas sensing, and the gating of ion-channels (10.1038/s41589-023-01411-5, 10.1021/acs.chemrev.5b00018). We have already made significant contributions to this field by using genetically-encoded fluorescence sensors to show that there is a significant abundance of free haem in the cytoplasm and nuclei of cells, enough to interfere with the behaviours of many cellular proteins (10.1073/pnas.2104008118).

Applicants for this PhD need to have an interest in spectroscopy and other physical measurement technique and enthusiasm to work at the life science interface.

Entry requirements:

Applicants are required to hold/or expect to obtain a UK Bachelor Degree 2:1 or better in a relevant subject or overseas equivalent.

The University of Leicester English language requirements apply

Informal enquiries:

Project Enquiries to: Professor Andrew Hudson andrew.hudson@le.ac.uk

General enquiries to pgrapply@le.ac.uk (please add Chemistry GTA to the subject line of your email)

TO APPLY

To apply please refer to https://le.ac.uk/study/research-degrees/funded-opportunities/chemistry-gta

University of Leicester

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