TY - JOUR
T1 - Mutations of human DNA topoisomerase I at poly (ADP-ribose) binding sites
T2 - Modulation of camptothecin activity by ADP-ribose polymers
AU - Tesauro, Cinzia
AU - Graziani, Grazia
AU - Arnò, Barbara
AU - Zuccaro, Laura
AU - Muzi, Alessia
AU - D'Annessa, Ilda
AU - Santori, Elettra
AU - Tentori, Lucio
AU - Leonetti, Carlo
AU - Fiorani, Paola
AU - Desideri, Alessandro
PY - 2014
Y1 - 2014
N2 - Background: DNA topoisomerases are key enzymes that modulate the topological state of DNA through the breaking and rejoining of DNA strands. Human topoisomerase I belongs to the family of poly(ADP-ribose)-binding proteins and is the target of camptothecin derived anticancer drugs. Poly(ADP-ribosyl)ation occurs at specific sites of the enzyme inhibiting the cleavage and enhancing the religation steps during the catalytic cycle. Thus, ADP-ribose polymers antagonize the activity of topoisomerase I poisons, whereas PARP inhibitors increase their antitumor effects. Methods: Using site-directed mutagenesis we have analyzed the interaction of human topoisomerase I and poly (ADP-ribose) through enzymatic activity and binding procedures. Results: Mutations of the human topoisomerase I hydrophobic or charged residues, located on the putative polymer binding sites, are not sufficient to abolish or reduce the binding of the poly(ADP-ribose) to the protein. These results suggest either the presence of additional binding sites or that the mutations are not enough perturbative to destroy the poly(ADP-ribose) interaction, although in one mutant they fully abolish the enzyme activity. Conclusions: It can be concluded that mutations at the hydrophobic or charged residues of the putative polymer binding sites do not interfere with the ability of poly(ADP-ribose) to antagonize the antitumor activity of topoisomerase I poisons.
AB - Background: DNA topoisomerases are key enzymes that modulate the topological state of DNA through the breaking and rejoining of DNA strands. Human topoisomerase I belongs to the family of poly(ADP-ribose)-binding proteins and is the target of camptothecin derived anticancer drugs. Poly(ADP-ribosyl)ation occurs at specific sites of the enzyme inhibiting the cleavage and enhancing the religation steps during the catalytic cycle. Thus, ADP-ribose polymers antagonize the activity of topoisomerase I poisons, whereas PARP inhibitors increase their antitumor effects. Methods: Using site-directed mutagenesis we have analyzed the interaction of human topoisomerase I and poly (ADP-ribose) through enzymatic activity and binding procedures. Results: Mutations of the human topoisomerase I hydrophobic or charged residues, located on the putative polymer binding sites, are not sufficient to abolish or reduce the binding of the poly(ADP-ribose) to the protein. These results suggest either the presence of additional binding sites or that the mutations are not enough perturbative to destroy the poly(ADP-ribose) interaction, although in one mutant they fully abolish the enzyme activity. Conclusions: It can be concluded that mutations at the hydrophobic or charged residues of the putative polymer binding sites do not interfere with the ability of poly(ADP-ribose) to antagonize the antitumor activity of topoisomerase I poisons.
KW - Camptothecin
KW - Cleavage
KW - PARP inhibitors
KW - PARylation
KW - Religation rate
KW - Topoisomerase I
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U2 - 10.1186/s13046-014-0071-z
DO - 10.1186/s13046-014-0071-z
M3 - Article
C2 - 25227992
AN - SCOPUS:84908213301
VL - 33
JO - Journal of Experimental and Clinical Cancer Research
JF - Journal of Experimental and Clinical Cancer Research
SN - 0392-9078
IS - 1
M1 - 71
ER -