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Effect of oxidative stress on the biochemistry of dimethylsulfoniopropionate (DMSP)-lyase enzymes in tropical reef organisms - to start October 2019 - for an MSc by Dissertation (MSD


Project Description

Rationale
Tropical coral reefs are a substantial source of the climate-cooling gas dimethyl sulfide (DMS). The major precursor of DMS is the secondary metabolite dimethylsulfoniopropionate (DMSP) that is biosynthesised to high concentrations in symbiotic dinoflagellates of the tropical genus Symbiodinium [1]. In the phytoplankton Emiliania huxleyi, the algal Alma DMSP-lyase enzymes are responsible for the production of DMS and Symbiodinium contains homologs of Ehux-Alma1 [2]. Despite their global importance, the biochemical function of DMSP and DMS in corals is underexplored. Since both operate as antioxidants that scavenge harmful reactive oxygen species (ROS) in E. huxleyi [3], the cycling of DMSP and DMS may have profound implications for the susceptibility of corals to ROS-induced lethal coral bleaching and the following destruction of reef environments.

Approach
Supported with an ongoing PhD project and in collaboration with King Abdullah University of Science and Technology (KAUST), we recently started building understanding of the dynamics of DMSP and DMS in the Aiptasia-Symbiodinum model system under physiological stress. Importantly, we grow Aiptasia-Symbiodinum combinations that show different susceptibilities to ROS-induced bleaching making this model system a preferred choice to study the function of DMSP/DMS under oxidative stress. Your MSD project will align with our ongoing efforts by investigating the biochemical basis of DMSP-to-DMS conversion in Symbiodinium and Aiptasia. With guidance from your supervisors, you will direct the project’s research emphasis and develop scientific hypotheses to assess the function of DMSP and DMS in the Aiptasia-Symbiodinum model system. The initial objectives and associated time scale are:
1. Conduct a literature review and use in-silico searches to identify homologs of Alma-like genes in the publicly available genomes of Symbiodinium and Aiptasia. [Months 1-2]
2. Purchase synthetic genes, and recombinantly express and purify Alma-like proteins in Escherichia coli cells. Confirm resulting DMSP-lyase activities using gas chromatographic enzyme assays. [Months 2-6]
3. Carry out biochemical analysis of Alma-like proteins and initiate crystallisation trials to pursue X-ray crystallography studies. [Months 5-7]
4. Grow clonal cultures of stress-resilient and stress-susceptible combinations of Symbiodinium and Aiptasia. [Months 3-5]
5. Synthesise [Month 3] and apply the specific Alma DMSP-lyase inhibitor 2-bromo-3-(dimethylsulfonio)-propionate (Br-DMSP) [4] to assess the biochemical functioning of DMSP-lyases in the stress physiology of Aiptasia, Symbiodinium and the Aiptasia-Symbiodinum holobiont. [Months 5-12]
6. Analyse data [Months 2-12] and prepare a thesis. [Months 10-12]
Feasibility and Training
This project uses methodologies that are well-established in our laboratories [e.g. 1] or published by others [2-4]. You will receive specific training to address the objectives 1 and 3 (supported by Hough), 2 (Worrall and Hough), 4 and 5 (Steinke with synthesis supported by Dr Sinan Battah), 6 (all supervisors).
You will work cross-disciplinarily with the Ecology and Environmental Microbiology and the Protein Structure and Mechanisms of Disease groups. Training and supervision will be supported by weekly meetings with the primary supervisor and at appropriate points with the additional supervisors. This project provides opportunity to gain skills sought after by industry and research employers, and presents excellent preparation to pursue PhD studies in biochemistry.

Funding Notes

Christine Desty Scholarship, fully-funded (Home/EU fees £4630 plus stipend of £15,009) for an MSc by Dissertation (MSD) in the School of Biological Sciences, University of Essex

References

1. Steinke, M., et al. 2011. Concentrations of dimethylsulfoniopropionate and dimethyl sulfide are strain-specific in symbiotic dinoflagellates ( Symbiodinium sp., Dinophyceae). Journal of Phycology 47(4): 775-783.
2. Alcolombri, U., et al. 2015. Identification of the algal dimethyl sulfide–releasing enzyme: A missing link in the marine sulfur cycle. Science 348(6242): 1466-1469.
3. Sunda, W., et al. 2002. An antioxidant function for DMSP and DMS in marine algae. Nature 418(6895): 317-320.
4. Alcolombri, U., et al. 2017. Assigning the Algal Source of Dimethylsulfide Using a Selective Lyase Inhibitor. ACS Chemical Biology 12(1): 41-46.

How good is research at University of Essex in Biological Sciences?

FTE Category A staff submitted: 23.00

Research output data provided by the Research Excellence Framework (REF)

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