An Insight Into the Mechanism of Inhibition of Unusual bi-Subunit Topoisomerase I from Leishmania donovani By 3,3�-di-indolylmethane, a novel DNA topoisomerase I poison with a strong binding affinity to the enzyme
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
An Insight Into the Mechanism of Inhibition of Unusual bi-Subunit Topoisomerase I from Leishmania donovani By 3,3�-di-indolylmethane,
a novel DNA topoisomerase I poison with a strong binding affinity
to the enzyme
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| Creator |
Roy, Amit
Das, Benu Brata Ganguly, Agneyo Bose Dasgupta, Somdeb Khalkho, Neeta V M Pal, Churala Dev, Sumit Giri, V S Jaisankar , P Dey, Sanjit Majumder, Hemanta K |
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| Subject |
Chemistry
Infectious Diseases and Immunology |
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| Description |
DIM (3,3�-di-indolylmethane), an abundant dietary component
of cruciferous vegetables, exhibits a wide spectrum of pharmacological
properties. In the present study, we show that DIM
is a potent inhibitor of Leishmania donovani topoisomerase I
with an IC50 of 1.2 μM. Equilibrium dialysis shows that DIM
binds strongly to the free enzyme with a binding constant
of 9.73×10−9 M. The binding affinity of DIM to the small
subunit is 8.6-fold more than that of the large subunit of unusual
LdTOP1LS (bi-subunit L. donovani topoisomerase I). DIM
stabilizes topoisomerase I–DNA cleavage complexes in vitro and
also in vivo. Like CPT (camptothecin), DIM inhibits the religation
step when the drug was added to preformed topoisomerase I–
DNA binary complex. Hence, DIM is similar to CPT with respect
to its ability to form the topoisomerase I-mediated ‘cleavable
complexes’ in vitro and in vivo. But unlike CPT, DIM interacts
with both free enzyme and substrate DNA. Therefore DIM is non-competitive class I inhibitor of topoisomerase I. DIM
also inhibits the relaxation activity of the CPT-resistant mutant
enzyme LdTOP1�39LS (N-terminal deletion of amino acids 1–
39 of LdTOP1LS). The IC50 values of DIM in simultaneous
and enzyme pre-incubation relaxation assays were 3.6 and
2.9 μM respectively, which are higher than that of wild-type
topoisomerase I (LdTOP1LS), indicating that the affinity of DIM
to LdTOP1�39LS is less than that for LdTOP1LS. This is the
first report on DIM as an L. donovani topoisomerase I poison.
Our study illuminates a new mode of action of enzyme inhibition
by DIM that might be exploited for rational drug design in human
leishmaniasis.
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| Date |
2008
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/293/1/BIOCHEMICAL_JOURNAL%2C_409%2C_611%2D622%2C2008[137].pdf
Roy, Amit and Das, Benu Brata and Ganguly, Agneyo and Bose Dasgupta, Somdeb and Khalkho, Neeta V M and Pal, Churala and Dev, Sumit and Giri, V S and Jaisankar , P and Dey, Sanjit and Majumder, Hemanta K (2008) An Insight Into the Mechanism of Inhibition of Unusual bi-Subunit Topoisomerase I from Leishmania donovani By 3,3�-di-indolylmethane, a novel DNA topoisomerase I poison with a strong binding affinity to the enzyme. Biochemical Journal, 409. pp. 611-622. |
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| Relation |
http://dx.doi.org/10.1042/BJ20071286
http://www.eprints.iicb.res.in/293/ |
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