Prions are novel protein-only infectious agents associated with a group of transmissible neurodegenerative diseases typified by human Creutzfeldt Jakob Disease (CJD). Although CJD are rare diseases, they share many pathological features with other more common, non-infectious diseases of the brain such as Alzheimer’s Disease. In spite of its infectious nature, the majority of cases of human CJD (~80%) appear spontaneously, without any evidence of the associated infectious entity, the prion. However, the molecular basis of how prions form spontaneously into infectious amyloid-like structures is poorly understood at present. Prions are also found in the yeast Saccharomyces cerevisiae and we are using one such prion – called [PSI+] – as a model to identify what triggers the spontaneous formation of a prion in the cell. This project will investigate the molecular mechanisms underlying the formation of prions during oxidative stress conditions.

• Sideri, T.C., Koloteva-Levine, N., Tuite, M.F. and Grant, C.M. Methionine oxidation of Sup35 induces formation of the [PSI⁺] prion in a yeast peroxiredoxin mutant. J. Biol. Chem. 286:38924-31
• Sideri, T.C., Stojanovski, K., Tuite, M.F. and Grant, C.M. (2010) Ribosome-associated peroxiredoxins suppress oxidative-stress induced de novo formation of the [PSI⁺] prion in yeast. Proc. Natl. Acad. Sci. U A. 107:6394-6399.
• Rand, J.D. and Grant, C.M. (2006) The Thioredoxin System Protects Ribosomes against Stress-induced Aggregation. Mol. Biol. Cell. 17: 387-401.

• Biochemistry
• Biomolecular Sciences
• Cell Biology
• Gene Expression
• Genetics
• Molecular Biology

This project has a Band 2 fee. Details of different fee bands are available for UK/EU or International applicants. See: Fees.

Carbohydrates make up most of the organic matter on earth and serve as major biological fuels. This has resulted in increasing interest in developing technology aimed at utilizing carbohydrates to produce biofuels. Lignocellulosic bioethanol production is particularly attractive in this regard since it offers an alternative source of carbohydrate to that already used as food sources. The main carbohydrate components of lignocellulose are glucose and xylose. Glucose serves as a primary biofuel for most organisms and can repress the synthesis of other carbon metabolizing enzymes through the effects of carbon catabolite repression. The objective of this proposal is to investigate the steps that limit the capacity of Saccharomyces cerevisiae to ferment xylose to ethanol and thus to identify how this process can be significantly improved, such that the utilisation of lignocellulose biomass by this organism can become a viable route to production of bioethanol. A major focus will be on the post-transcriptional control of mRNAs expressing key components of xylose metabolism. Our preliminary experiments indicate that the pathways of xylose breakdown are regulated by both transcriptional and translational mechanisms, and it is only by considering all of gene expression that we can truly understand the production of bioethanol from lignocellulose. 

• Biochemistry
• Biomolecular Sciences
• Biotechnology
• Gene Expression
• Genetics
• Molecular Biology

This project has a Band 2 fee. Details of different fee bands are available for UK/EU or International applicants. See: Fees.

The introduction of whole biochemical pathways into micro-organisms for the production of useful products such as biofuels is now a major focus of the biotechnology industry. In particular, processes that make use of waste material by converting it into useful products have received great attention: for example, the use of lignocellulosic waste for the production of bioethanol by yeast. The yeast S. cerevisiae is a workhorse of this industry, as well as a key model system in the study of molecular and cellular biology. This yeast does not naturally metabolise the 5 carbon sugar xylose; it requires the addition of several exogenous genes to achieve this. Pentose sugars such as xylose are key breakdown products of lignocellulose; therefore, there is great interest in forcing yeast to metabolise these sugars in order to improve yields of bioethanol from lignocellulose. In this project, we aim to invetsigate whether co-ordinated localisation of the mRNAs for the various added genes leads to improved expression and ultimately higher bioethanol yields. In the first part, the project will start by characterising regulatory elements that govern mRNA localisation within yeast cells. Then using this knowledge strains will be designed and constructed bearing the xylose metabolic pathway with and without these control elements to evaluate the impact on pathway flux.

• Castelli LM, Lui J, Campbell SG, Rowe W, Zeef LA, Holmes LE, Hoyle NP, Bone J, Selley JN, Sims PF, Ashe MP. 2011. Glucose depletion inhibits translation initiation via eIF4A loss and subsequent 48S preinitiation complex accumulation, while the pentose phosphate pathway is coordinately up-regulated. Mol Biol Cell. 22: 3379-93
• Lui J, Campbell SG, Ashe MP. 2010. Inhibition of translation initiation following glucose depletion in yeast facilitates a rationalization of mRNA content. Biochem Soc Trans. 38:1131.
• Hoyle NP, Castelli LM, Campbell SG, Holmes LE,  Ashe MP.  2007.  Stress-dependent relocalization of translationally primed mRNPs to cytoplasmic granules that are kinetically and spatially distinct from P-bodies.  J Cell Biol. 179: 65.

• Biotechnology
• Cell Biology
• Gene Expression
• Genetics
• Microbiology
• Molecular Biology

This project has a Band 2 fee. Details of different fee bands are available for UK/EU or International applicants. See: Fees.

• Biochemistry
• Biomolecular Sciences
• Biotechnology
• Cell Biology
• Molecular Cancer Studies
• Organelle Function
• Structural Biology

This project has a Band 2 fee. Details of different fee bands are available for UK/EU or International applicants. See: Fees.

Oxidative stress is a major biological problem which has a causal relationship with many disease processes including cancer, neurodegenerative and cardiovascular diseases. All organisms are exposed to reactive oxygen species (ROS) during the course of normal aerobic metabolism or following exposure to radical-generating compounds. In addition, the generation of ROS by neutrophils and macrophages is an important component of immunological defences against pathogens. ROS cause wide-ranging damage to macromolecules eventually leading to cell death.  Cells must be able to maintain their intracellular homeostasis in the face of changing conditions. Typically, they respond by invoking complex regulatory mechanisms including a global inhibition of translation. This reduction in protein synthesis may prevent continued gene expression during potentially error-prone conditions as well as allow for the turnover of existing mRNAs and proteins whilst gene expression is reprogrammed to deal with the stress. The aim of this project is to identify how oxidative stress regulates the translation machinery to control protein synthesis in yeast and the fungal pathogen Candida albicans.

• Shenton, D., Smirnova, J.B., Selley, J.N., Carroll, K., Hubbard, S.J., Pavitt, G.D., Ashe, M,P. and Grant, C.M. (2006) Global translational responses to oxidative stress impact upon multiple levels of protein synthesis. J. Biol. Chem. 281: 29011-29021.
• Mascarenhas, M., Edwards-Ingram, L. C., Zeef, L., Shenton, L., Ashe, M. P., and Grant, C. M. (2008) Gcn4 is required for the response to peroxide stress in the yeast Saccharomyces cerevisiae Mol. Biol. Cell 19: 2995-3007
• Cridge, A.E., Smirnova, J.B.c Selley, J.N., Hubbard, S., McCarthy, J.E., Ashe, M.P., Grant, C.M. and Pavitt, G.D. (2010) Identifying eIF4E-binding protein controlled transcripts reveals links to mRNAs bound by specific PUF proteins. Nucl. Acids Res. 38:8039-50.

• Biochemistry
• Biomolecular Sciences
• Cell Biology
• Gene Expression
• Genetics
• Molecular Biology

This project has a Band 2 fee. Details of different fee bands are available for UK/EU or International applicants. See: Fees.