Prediction and functional analysis of DNA topoisomerase Ⅱ β-binding protein 1（TopBP1） phosphorylation sites

Abstract:

To elucidate the molecular mechanism of DNA topoisomerase Ⅱ binding protein 1 (TopBP1) involved in DNA damage repair response, this study found several potential phosphorylation sites (T860, S887, T1104 and T1167) of TopBP1 through bioinformatics analysis. The TopBP1 was amplified from the human cDNA library and cloned into plasmid via molecular biology,and the above phosphorylation site was mutant to alanine to observe the response of the cells transfected with the mutant plasmid to DNA damage repair. Results showed that TopBP1 protein with the 1104th alanine mutation (T1104A) significantly reduced the phosphorylation level of pRPA32-S33 and inactivated the cell cycle checkpoint after the irradiation or chemotherapy drug treatment, which severely blocked DNA stress response. This study confirms that T1104 is the key activity site of TopBP1 involved in DNA damage repair.