Unveiling a key enzyme in global sulfur cycling
Background: Billions of tonnes of the osmolyte dimethysulfonioproprionate (DMSP) are produced annually in Earth’s oceans by many algae and bacteria. These organisms produce DMSP at mM intracellular concentrations for protection against varied stresses. When released into the environment, microorganisms import and catabolise DMSP, generating the climate-cooling gas and signalling molecule dimethylsulfide (DMS) via DMSP lyase enzymes. However, marine microbes can also oxidise DMSP to form dimethylsulfoxoniumpropionate (DMSOP) via unidentified enzymes. Importantly, this novel step in the global sulfur cycle potentially limits the release of climate-active gases. Abundant bloom-forming algae and bacteria produce DMSOP at high intracellular levels, but it is unknown how or why these processes occur at the molecular, physiological and environmental levels. This PhD will conduct interdisciplinary research to identify and characterise the enzymes involved in DMSOP synthesis and their regulation in model and abundant marine bacteria that make DMSOP. The importance of DMSOP synthesis will be further investigated through analysis of the biodiversity, prominence, expression and biogeography of identified genes in diverse environments.
Research methodology and training: You will join well-resourced and vibrant labs that provided step changes to the understanding of DMSP/DMSOP biology and marine sulfur cycling. Expert multidisciplinary training will be provided in analytical chemistry techniques to monitor DMSOP synthesis; molecular microbiology technologies, e.g., generation of knockout mutations; enzymology and bioinformatics to assess the biogeography, magnitude and environmental significance of DMSOP production.
Supervision: You will discuss your findings at weekly team and supervisory meetings, where your progress will be monitored and training needs assessed. You will attend and present work at high-profile national and international scientific conferences, which will aid your writing of peer-reviewed scientific publications and your PhD thesis.
Person specification: We are looking for a highly motivated applicant with strong interests in molecular microbiology and who can thrive in a multidisciplinary research laboratory.
References
Thume K, Gebser B, Chen L, Meyer N, Kieber DJ, Pohnert G. (2018). The metabolite dimethylsulfoxonium propionate extends the marine organosulfur cycle. Nature. 563:412-415.
Curson ARJ, Williams BT, Pinchbeck BJ, Sims LP, Martínez AB, Rivera PPL, Kumaresan D, Mercadé E, Spurgin LG, Carrión O, Moxon S, Cattolico RA, Kuzhiumparambil U, Guagliardo P, Clode PL, Raina JB, Todd JD*. (2018). DSYB catalyses the key step of dimethylsulfoniopropionate biosynthesis in many phytoplankton. Nature Microbiology. 4:430-439.
Hopkins FE, Archer SD, Bell TG, Suntharalingam P, Todd JD*. (2023). The biogeochemistry of marine dimethylsulfide. Nature Reviews Earth & Environment. 4:361-376.
Carrión O, Li C, Peng M, Wang J, Pohnert G, Azizah M, Zhu XY, Curson ARJ, Wang Q, Walsham KS, Zhang XH, Monaco S, Harvey JM, Chen XL, Gao C, Wang N, Wang XJ, Wang P, Giovanonni SJ, Lee CP, Suffridge CP, Zhang Y, Luo Z, Wang D, Todd JD*, Zhang YZ. (2023). DMSOP-cleaving enzymes are diverse and widely distributed in marine microorganisms. Nature Microbiology. 8:2326-2337.
Wang J, Curson ARJ, Zhou S, Carrión O, Liu J, Vieira AR, Walsham KS, Monaco S, Li CY, Dong QY, Wang Y, Rivera PPL, Wang XD, Zhang M, Hanwell L, Wallace M, Zhu XY, Leão PN, Lea-Smith DJ, Zhang YZ, Zhang XH, Todd JD*. (2024). Alternative dimethylsulfoniopropionate biosynthesis enzymes in diverse and abundant microorganisms. Nature Microbiology. https://doi.org/10.1038/s41564-024-01715-9.