Congratulation Christos!
On 7 October 2024, Christos Theodorou was awarded his PhD degree after defending his thesis titled "Untargeted Metabolomics as a Tool for the Elucidation of Transporter Protein Substrate Specificity" at the Faculty of Science. The defense took place in the presence of friends and colleagues, marking the culmination of his research journey.
Summary of the thesis
In plants, transporter proteins are involved in multiple cellular processes such as maintaining homeostasis, signalling and cell communication as well as uptake or efflux of specialized metabolites among different compartments. However, our knowledge about the function of the many transporters in the genomes is limited. In the DynaMo Center, Christos Theodorou has been part of the VILLUM investigator project aimed at identification of transporter substrate specificity in a major transportomics endeavor.
Christos has played a key role in development of a novel transportomics methodology that combines the use of uptake assays with plant extracts as complex substrate mixtures, and untargeted metabolomics as an analytical tool, therefore allowing for the simultaneous testing of multiple compounds against the same transporter. In the thesis, Christos describes all steps, from the creation of the substrate mixture to the generation of the analytical pipeline for screening transporter proteins with the ‘transportomics’ pipeline. This includes the experimental set-up and the subsequent data acquisition, preprocessing and statistical analysis techniques comprising the developed pipeline based on a dataset of transporter proteins with unknown functionality.
Christos has conducted a thorough investigation on different extracts that can be used as substrate mixtures in the transportomics pipeline and use an innovative approach to maximize the metabolic diversity contained within that mixture. He performed an in-depth metabolic profiling of the selected plant extract based on a combinatorial technique leading to the identification of more than 200 metabolites.
Through collaboration with other members who are part of this VILLUM investigator grant, the performance of the developed pipeline was validated based on two different study cases that are used as a proof of concept and present the first-of-its-kind export transportomics assay. Several substrates for four different transporter proteins belonging to different protein families were identified.
Principal supervisors:
Professor Barbara Ann Halkier, Section for Molecular Plant Biology
Facility manager Christoph Crocoll, Section for Molecular Plant Biology
The assessment committee consisted of:
Associate professor Giorgia La Barbera, Department of Nutrition and Health (Chair)
Professor Robert David Hall, Wageningen University and Research, the Netherlands (External member)
Assistant professor Daniel Petras, Department of Biochemistry, University of California, US (External member)
Christos will continue as postdoc for another two years at the DynaMo Center.