Studies On The Interaction Of Euplotes Octocarinatus Centrin And DNA

DNA(deoxyribonucleic),carryies genetic information, is the most important macromolecules in the organism.DNA always be damaged because of physical and chemical factors contain hydrolytic damage, Alkylation Damage, oxidative damage, ionizing radiation, UV-Induced damage that cause DNA base lost or changed, nucleotide insertions or deletion. If such damage can not be repaired, the functions of cells will be effected.We know the DNA pathways have direct repair, excision repair, recombination repair, there excision repair contains base excision repair and nucleotide excision repair.Protein-DNA interactions play a crucial role in many life processes, such as the regulation of gene experession, DNA replication and repair. The main force is van der Waals, hydrogen bonding.The most interactions are non-specific, there the specificity of the interaction is determined by the base and the amino acid residues between the hydrogen bond.Here, we select centrin fragment P23, pBR322DNA and CT-DNA to study their interactions, using the methods of fluorescence, agrose gel electrophoresis and GST pull-down.TNS fluorescence studies shows that CT-DNA can bond the hydrophic of P23, making the hydrophobic exposure more, Ca2+can significantly promote them to bind, while the Tb3+can bind with CT-DNA, that the role is not obvious.EB fluorescence also demonstrate P23can bind with CT-DNA, Ca2+, Tb3+play the role of promoting. Tb3+fluorescence shows P23and CT-DNA both can sensitize Tb3+fluorescence, and the capacity order of Tb3+binding P23, CT-DNA is the third domain of P23>CT-DNA>the second domain of P23.Agrose gel electrophoresis experiments show that P23can cleavage pBR322DNA, Tb3+and Ca2+have catalytic roles, and the promote order is Ca2+>Tb3+, free radical trapping experiments preliminary infer the cleavage mechanism is hydrolysis cutting.GST pull-down, a common molecular biology method, always be used to stdudy the interaction of protein and protein. We use this method to investigate centrin P23interacting with CT-DNA, the experiments obtain the same conclusion as before, P23can combine CT-DNA, and Ca2+could significantly promote them to bind, while Tb3+does not show obvious ptomoting activity.