1SR4 image
Entry Detail
PDB ID:
1SR4
Keywords:
Title:
Crystal Structure of the Haemophilus ducreyi cytolethal distending toxin
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2004-03-22
Release Date:
2004-06-15
Method Details:
Experimental Method:
Resolution:
2.00 Å
R-Value Free:
0.21
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Cytolethal distending toxin subunit A
Chain IDs:A
Chain Length:206
Number of Molecules:1
Biological Source:Haemophilus ducreyi
Polymer Type:polypeptide(L)
Description:cytolethal distending toxin protein B
Chain IDs:B
Chain Length:261
Number of Molecules:1
Biological Source:Haemophilus ducreyi
Polymer Type:polypeptide(L)
Description:cytolethal distending toxin protein C
Chain IDs:C
Chain Length:166
Number of Molecules:1
Biological Source:Haemophilus ducreyi
Ligand Molecules
Primary Citation
Assembly and Function of a Bacterial Genotoxin
Nature 429 429 433 (2004)
PMID: 15164065 DOI: 10.1038/nature02532

Abstact

The tripartite cytolethal distending toxin (CDT) induces cell cycle arrest and apoptosis in eukaryotic cells. The subunits CdtA and CdtC associate with the nuclease CdtB to form a holotoxin that translocates CdtB into the host cell, where it acts as a genotoxin by creating DNA lesions. Here we show that the crystal structure of the holotoxin from Haemophilus ducreyi reveals that CDT consists of an enzyme of the DNase-I family, bound to two ricin-like lectin domains. CdtA, CdtB and CdtC form a ternary complex with three interdependent molecular interfaces, characterized by globular, as well as extensive non-globular, interactions. The lectin subunits form a deeply grooved, highly aromatic surface that we show to be critical for toxicity. The holotoxin possesses a steric block of the CdtB active site by means of a non-globular extension of the CdtC subunit, and we identify putative DNA binding residues in CdtB that are essential for toxin activity.

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Primary Citation of related structures