Swapping of The N-Terminal Domain of Human Topoisomerase 1B with the Corresponding Plasmodium Falciparum Counterpart Strongly Impairs Enzyme Activity

AbstractBackground:DNA topoisomerases 1B are a class of ubiquitous enzyme that solves the topological problemsassociated with biological processes such as replication, transcription and recombination. Numerous sequencealignment of topoisomerase 1B from different species shows that the lengths of different domains as well astheir amino acids sequences are quite different. In the present study a hybrid enzyme, generated by swappingthe N-terminal of Plasmodium falciparum into the corresponding domain of the human, has beencharacterized.Methods:The chimeric enzyme was generated using different sets of PCR. The in vitro characterization wascarried out using different DNA substrate including radio-labelled oligonucleotides.Results: The chimeric enzyme displayed slower relaxation activity, cleavage and re-ligation kinetics stronglyperturbed when compared to the human enzyme.Conclusions:These results indicate that the N-terminal domain has a crucial role in modulating topoisomeraseactivity in different species.