Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2067/47370
Titolo: Effect on DNA relaxation of the single Thr718Ala mutation in human topoisomerase I: a functional and molecular dynamics study
Autori: Chillemi, Giovanni 
Fiorani, Paola
Castelli, Silvia
Bruselles, Alessandro
Benedetti, Piero
Desideri, Alessandro
Data pubblicazione: 2005
The functional and dynamical properties of the human topoisomerase I Thr718Ala mutant have been compared to that of the wild-type enzyme using functional assays and molecular dynamics (MD) simulations. At physiological ionic strength, the cleavage and religation rates, evaluated on oligonucleotides containing the preferred topoisomerase I DNA sequence, are almost identical for the wild-type and the mutated enzymes, as is the cleavage/religation equilibrium. On the other hand, the Thr718Ala mutant shows a decreased efficiency in a DNA plasmid relaxation assay. The MD simulation, carried out on the enzyme complexed with its preferred DNA substrate, indicates that the mutant has a different dynamic behavior compared to the wild-type enzyme. Interestingly, no changes are observed in the proximity of the mutation site, whilst a different flexibility is detected in regions contacting the DNA scissile strand, such as the linker and the V-shaped alpha helices. Taken together, the functional and simulation results indicate a direct communication between the mutation site and regions located relatively far away, such as the linker domain, that with their altered flexibility confer a reduced DNA relaxation efficiency. These results provide evidence that the comprehension of the topoisomerase I dynamical properties are an important element in the understanding of its complex catalytic cycle.
URI: http://hdl.handle.net/2067/47370
ISSN: 0305-1048
DOI: 10.1093/nar/gki642
Diritti: CC0 1.0 Universal
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