1k4s: Difference between revisions

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New page: left|200px<br /> <applet load="1k4s" size="450" color="white" frame="true" align="right" spinBox="true" caption="1k4s, resolution 3.20Å" /> '''HUMAN DNA TOPOISOME...
 
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[[Image:1k4s.gif|left|200px]]<br />
[[Image:1k4s.gif|left|200px]]<br /><applet load="1k4s" size="350" color="white" frame="true" align="right" spinBox="true"  
<applet load="1k4s" size="450" color="white" frame="true" align="right" spinBox="true"  
caption="1k4s, resolution 3.20&Aring;" />
caption="1k4s, resolution 3.20&Aring;" />
'''HUMAN DNA TOPOISOMERASE I IN COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX'''<br />
'''HUMAN DNA TOPOISOMERASE I IN COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX'''<br />


==Overview==
==Overview==
We report the x-ray crystal structure of human topoisomerase I covalently, joined to double-stranded DNA and bound to the clinically approved, anticancer agent Topotecan. Topotecan mimics a DNA base pair and binds at, the site of DNA cleavage by intercalating between the upstream (-1) and, downstream (+1) base pairs. Intercalation displaces the downstream DNA, thus preventing religation of the cleaved strand. By specifically binding, to the enzyme-substrate complex, Topotecan acts as an uncompetitive, inhibitor. The structure can explain several of the known, structure-activity relationships of the camptothecin family of anticancer, drugs and suggests that there are at least two classes of mutations that, can produce a drug-resistant enzyme. The first class includes changes to, residues that contribute to direct interactions with the drug, whereas a, second class would alter interactions with the DNA and thereby destabilize, the drug-binding site.
We report the x-ray crystal structure of human topoisomerase I covalently joined to double-stranded DNA and bound to the clinically approved anticancer agent Topotecan. Topotecan mimics a DNA base pair and binds at the site of DNA cleavage by intercalating between the upstream (-1) and downstream (+1) base pairs. Intercalation displaces the downstream DNA, thus preventing religation of the cleaved strand. By specifically binding to the enzyme-substrate complex, Topotecan acts as an uncompetitive inhibitor. The structure can explain several of the known structure-activity relationships of the camptothecin family of anticancer drugs and suggests that there are at least two classes of mutations that can produce a drug-resistant enzyme. The first class includes changes to residues that contribute to direct interactions with the drug, whereas a second class would alter interactions with the DNA and thereby destabilize the drug-binding site.


==Disease==
==Disease==
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==About this Structure==
==About this Structure==
1K4S is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Active as [http://en.wikipedia.org/wiki/DNA_topoisomerase DNA topoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.99.1.2 5.99.1.2] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1K4S OCA].  
1K4S is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Active as [http://en.wikipedia.org/wiki/DNA_topoisomerase DNA topoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.99.1.2 5.99.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K4S OCA].  


==Reference==
==Reference==
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[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Single protein]]
[[Category: Single protein]]
[[Category: Behnke, C.A.]]
[[Category: Behnke, C A.]]
[[Category: Feese, M.D.]]
[[Category: Feese, M D.]]
[[Category: Hjerrild, K.]]
[[Category: Hjerrild, K.]]
[[Category: Jr., A.B.Burgin.]]
[[Category: Jr., A B.Burgin.]]
[[Category: Staker, B.L.]]
[[Category: Staker, B L.]]
[[Category: Stewart, L.J.]]
[[Category: Stewart, L J.]]
[[Category: complex (isomerase/dna)]]
[[Category: complex (isomerase/dna)]]
[[Category: dna]]
[[Category: dna]]
[[Category: topoisomerase i]]
[[Category: topoisomerase i]]


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