1sr4

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Template:STRUCTURE 1sr4

Crystal Structure of the Haemophilus ducreyi cytolethal distending toxin

Overview

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.

About this Structure

1SR4 is a Protein complex structure of sequences from Haemophilus ducreyi. Full crystallographic information is available from OCA.

Reference

Assembly and function of a bacterial genotoxin., Nesic D, Hsu Y, Stebbins CE, Nature. 2004 May 27;429(6990):429-33. PMID:15164065 Page seeded by OCA on Sat May 3 09:03:02 2008