Primær analyse av catalase i Arabidopsis thaliana
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Catalase is involved in the protection of the cell against reactive oxygen species (ROS), though the detoxification of hydrogen peroxide (H2O2) in the peroxisomes. If not destroyed or controlled ROS can lead to damage of the cell and even kill the cell. H2O2 can also act as a signaling molecule and in this way be a natural part of the organism’s way of surviving in the environment. This can put catalase in a different light, with the possibility of having a more complex and wider function than previously thought. The full role and function of catalase is therefore yet to be discovered. Studies have shown that catalase can have some activity outside the peroxisomes, in the cytosol or in the mitochondria. This raises the suspicion if catalase could have an interaction with cytosolic proteins, such as DJ-1. DJ-1 has an interaction with SOD and GPX. SOD and GPX are involved in the conversion of O2- to H2O2 and further to H2O. This is also the main role of catalase. It is therefore believed that catalase can in this manner have an interaction with DJ-1. DJ- 1, called PARK 7 (in human beings) is one of the main Parkinson`s disease related protein. Parkinson`s disease is a disorder that blocks post- synaptic signaling and leads to neurodegeneration. This is caused by environmental and genetic factors that might lead to the accumulation of ROS in the cell. This accumulation (if not handled by the cell) causes mutations in the genes involved and disrupts the pathway of dopamine transfer across neurons with the outcome of aggregation of Lewy Bodies. In this thesis the catalases in Arabidopsis thaliana were analyzed. Catalase localization and interaction with DJ-1 and other ROS related proteins were analyzed. Knock out mutant plants and plants with over- expressed catalase were observed with regard to their phenotype. Levels of catalase in plants of different age and in different plant tissue were also checked. Out of the three variants of catalases in A. thaliana, AtCat3 had the highest expression level (relative stable over time), AtCat1 had the second highest expression level (decreasing over time) and AtCat2 had the lowest expression (nearly not detectable). AtCat3 had its highest expression in leaf, stem and seed couples (measured after 4 weeks of growth in soil) and AtCat1 had its highest expression in stem and leaf (measured after 4 weeks of growth in soil). Expression of AtCat2 in different plant tissue after 4 weeks of growth in soil was too low to measure. Catalase expression in flower was relatively low for both AtCat1 and AtCat3. By doing research on the genes involved in Parkinson`s disease, the mechanism behind the disorder can fully be discovered and this can make it possible to understand the disorder on a deeper level.
Master's thesis in Biological Chemistry