Plant protein phosphorilation

Šimac, Matija (2010) Plant protein phosphorilation. Bachelor's thesis, Faculty of Science > Department of Biology.

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Signaling in plants and photosynthesis are in a very close relationship. Photosynthesis is a very important mechanism that offers asimilates required for plant growth and growth for all other organisms depending on plants. Protein-protein interactions play a very important role in cellular processes such as signal transduction, regulation of the life cycle of cells, metabolic regulation. Therefore, regulation of protein interactions at a specific time and space is very important for the survival on the cellular level and for an organism. Reversible phosphorylation of specific amino acid residue within the phosphoprotein-binding domain of protein kinase target protein, can cause changes in conformation and charge. These changes may lead to the formation of docking places for fosfopeptid-binding proteins on the target protein. In light conditions the enzyme is in its active dephosphorylated form. Nitrate reductase is one of the first enzymes discovered that bind to 14-3-3 proteins. Later it was proved that 14-3-3 proteins are signaling proteins that bind to serin and threonin. Phosphorylated serine residues interact with various proteins (known as client proteins) in plants and animals. 14-3-3 proteins bind phosphorylated proteins in a cleft between the subunits, binding to simple motifs that include phosphorylated threonin or serine residues (pS or pT). In some cases, the binding of 14-3-3 with nitrate reductase was inhibited, as in some cases cations have almost no role in binding. All cations affect the same protein interactions, which suggest that changes in cation conentation, (such as stress response), will change the tendency of 14-3-3 protein binding to different targets. The level of protein phosphorylation also changes in response to ROS. They are produced in many parts of the cell as response to hormones that regulate normal plant growth and development as well as a variety of abiotic and biotic stresses. Methionine residue is very hydrophobic in reduced form. Mild reversible oxidation produces a much more polar sulfoxide (MetSO). This modification repairs peptide methionine sulfoxide reductase, but plant and animal cells in basal metabolism will always have a few residue of the MetSO. Stronger oxidation results in an irreversible conversion into the sulfone (MetO2 ) that can only be repaired by protein degradation. It is possible that this propensity for methionine residues to oxidize may be exploited in response to signalling by ROS.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Balen, Biljana
Date: 2010
Number of Pages: 9
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 02 Dec 2014 11:54
Last Modified: 02 Dec 2014 11:54

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