cecilie_cetti_hansen – University of Copenhagen

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Center for Synthetic Biology > Meet the Researchers > cecilie_cetti_hansen

Cecilie Cetti Hansen

PhD student

Cyanogenic glucosides group
Section for Plant Biochemitry
Department for Plant and Environmental Sciences
Faculty of Science

cich@plen.ku.dk

NADPH-dependent cytochrome P450 oxiodoreductase (POR) plays an essential role in plant metabolism, donating electrons to the important large enzyme family, the cytochromes P450 (P450). Each higher plant species possesses more than hundred different P450s, which carry out fundamental roles in general and specialized metabolism such as the synthesis of essential hormones and bio-active natural products. In contrast, each separate plant species usually possesses 1 to 3 different PORs present in sub-stoichiometric amounts compared to the total level of P450s present. Specific orchestration of the electron transfer processes from a POR to a specific P450 is thus required in the course of plant growth and development and to enable the plant to respond to biotic and abiotic stresses encountered.

Cyanogenic glucosides, a class of amino acid-derived defence compounds, are biosynthesized by the combined action of P450s, PORs and glycosyltransferases. The well-characterized biosynthetic pathway of the cyanogenic glucoside dhurrin from Sorghum bicolor and the newly identified biosynthetic pathway of prunasin from Eucalyptus cladocalyx are used as model systems to study interactions between PORs and P450s.  Special focus is on the assembly and structural organization of the transient enzyme complexes (metabolons) involved.

POR undergoes conformational changes during the electron transfer cycle to P450. It is hypothesized that the conformational dynamics of POR could be functionally relevant for activation of different P450s. The conformational dynamics are typically averaged out in bulk assays. However, single molecule studies provide the possibility to observe heterogeneities and the distribution of behaviors of the molecular individuals in a population. I collaborate with Ass. Prof. Nikos Hatzakis’s group on single molecule studies to unravel the dynamics of POR paralogs in plants.

Another part of my PhD project focuses on the effect of climate change on the formation and accumulation of different classes of specialized metabolites in eucalypts and the biosynthesis of these compounds. Untargeted metabolomics and transcriptomics are applied to get insight in how Eucalyptus respond to elevated temperature and CO2.

Besides my studies on POR and P450s, I’m a supervisor for the UCPH iGEM 2017 team, InCell. I have also advised the 2015 team SpaceMoss and the 2016 team CosmoCrops. In find it very interesting to work with an interdisciplinary team and follow the students work with synthetic biology.