ATP Independent Type IB Topoisomerase of Leishmania Donovani is Stimulated by ATP: an Insight into the Functional Mechanism

Sengupta, Souvik and Ganguly, Agneyo and Roy, Amit and Somdeb, Bose Dasgupta and D’Annessa, IIDA and Desideri, Alessandro and Majumder, Hemanta K (2011) ATP Independent Type IB Topoisomerase of Leishmania Donovani is Stimulated by ATP: an Insight into the Functional Mechanism. Nucleic Acids Research, 39 (8). pp. 3295-3309.

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    Abstract

    Most type IB topoisomerases do not require ATP and Mg2+for activity. However, as shown previously for vaccinia topoisomerase I, we demonstrate that ATP stimulates the relaxation activity of the unusual heterodimeric type IB topoisomerase from Leishmania donovani (LdTOP1L/S) in the absence of Mg2+. The stimulation is independent of ATP hydrolysis but requires salt as a co-activator. ATP binds to LdTOP1L/S and increases its rate of strand rotation. Docking studies indicate that the amino acid residues His93, Tyr95, Arg188 and Arg190 of the large subunit may be involved in ATP binding. Site directed mutagenesis of these four residues individually to alanine and subsequent relaxation assays reveal that the R190A mutant topoisomerase is unable to exhibit ATP-mediated stimulation in the absence of Mg2+. However, the ATP-independent relaxation activities of all the four mutant enzymes remain unaffected. Additionally, we provide evidence that ATP binds LdTOP1L/S and modulates the activity of the otherwise ATP-independent enzyme. This study establishes ATP as an activator of LdTOP1L/S in the absence of Mg2+.

    Item Type: Article
    URI: http://www.eprints.iicb.res.in/id/eprint/112
    Subjects: Infectious Diseases and Immunology
    Divisions: Indian Institute of Chemical Biology
    Depositing User: Mr Santanu Sadhukhan
    Date Deposited: 29 Sep 2011 12:44
    Last Modified: 22 Jan 2013 15:05
    Official URL: http://dx.doi.org/10.1093/nar/gkq1284
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