1K4T

HUMAN DNA TOPOISOMERASE I (70 KDA) IN COMPLEX WITH THE POISON TOPOTECAN AND COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.229 

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Ligand Structure Quality Assessment 


This is version 1.2 of the entry. See complete history


Literature

The mechanism of topoisomerase I poisoning by a camptothecin analog

Staker, B.L.Hjerrild, K.Feese, M.D.Behnke, C.A.Burgin Jr., A.B.Stewart, L.J.

(2002) Proc Natl Acad Sci U S A 99: 15387-15392

  • DOI: 10.1073/pnas.242259599
  • Primary Citation of Related Structures:  
    1K4S, 1K4T

  • PubMed Abstract: 
  • 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 ...

    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.


    Organizational Affiliation

    deCODE genetics, Incorporated, BioStructures Group, 7869 Northeast Day Road West, Bainbridge Island, WA 98110, USA.



Macromolecules

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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
DNA topoisomerase ID [auth A]592Homo sapiensMutation(s): 1 
Gene Names: TOP1
EC: 5.99.1.2 (PDB Primary Data), 5.6.2.1 (UniProt)
UniProt & NIH Common Fund Data Resources
Find proteins for P11387 (Homo sapiens)
Explore P11387 
Go to UniProtKB:  P11387
PHAROS:  P11387
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP11387
Protein Feature View
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  • Reference Sequence

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Entity ID: 1
MoleculeChainsLengthOrganismImage
5'-D(*AP*AP*AP*AP*AP*GP*AP*CP*TP*T)-3'A [auth B]10N/A
Protein Feature View
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  • Reference Sequence

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Entity ID: 2
MoleculeChainsLengthOrganismImage
5'-D(*(TGP)P*GP*AP*AP*AP*AP*AP*TP*TP*TP*TP*T)-3'B [auth C]12N/A
Protein Feature View
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  • Reference Sequence

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Entity ID: 3
MoleculeChainsLengthOrganismImage
5'-D(*AP*AP*AP*AP*AP*TP*TP*TP*TP*TP*CP*CP*AP*AP*GP*TP*CP*TP*TP*TP*TP*T)-3'C [auth D]22N/A
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
TTG
Query on TTG

Download Ideal Coordinates CCD File 
E [auth C]2-(1-DIMETHYLAMINOMETHYL-2-HYDROXY-8-HYDROXYMETHYL-9-OXO-9,11-DIHYDRO-INDOLIZINO[1,2-B]QUINOLIN-7-YL)-2-HYDROXY-BUTYRIC ACID
C23 H25 N3 O6
DPQJTQJZJNYUEC-QHCPKHFHSA-N
 Ligand Interaction
TTC
Query on TTC

Download Ideal Coordinates CCD File 
F [auth D](S)-10-[(DIMETHYLAMINO)METHYL]-4-ETHYL-4,9-DIHYDROXY-1H-PYRANO[3',4':6,7]INOLIZINO[1,2-B]-QUINOLINE-3,14(4H,12H)-DIONE
C23 H23 N3 O5
UCFGDBYHRUNTLO-QHCPKHFHSA-N
 Ligand Interaction
HG
Query on HG

Download Ideal Coordinates CCD File 
G [auth A]MERCURY (II) ION
Hg
BQPIGGFYSBELGY-UHFFFAOYSA-N
 Ligand Interaction
PG4
Query on PG4

Download Ideal Coordinates CCD File 
H [auth A]TETRAETHYLENE GLYCOL
C8 H18 O5
UWHCKJMYHZGTIT-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
PTR
Query on PTR
D [auth A]L-PEPTIDE LINKINGC9 H12 N O6 PTYR
Binding Affinity Annotations 
IDSourceBinding Affinity
TTC BindingDB:  1K4T Kd: 26.5 (nM) from 1 assay(s)
IC50: min: 21, max: 2.00e+4 (nM) from 11 assay(s)
EC50: min: 54, max: 71.3 (nM) from 2 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.229 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.093α = 90
b = 116.26β = 94.16
c = 75.217γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
CNXrefinement
CNXphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-12-04
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance